Configure CircleCI for GUI tests

[andresriancho]

Xpresser GUI tests need to PASS in CircleCI too.

This will be a complex task to achieve, some ideas and notes:

• Xvfb is running on :99 https://circleci.com/docs/environment#browsers
• Debugging with X forwarding https://circleci.com/docs/browser-debugging#x11-forwarding-over-ssh
• I think I'll have to install gnome or some other window manager since some screenshots (damn, why did I choose xpresser!) have parts of the window decoration

[andresriancho]

These are the tests that will be run when this has been setup:

w3af.core.ui.console.tests.test_ctrl_c.TestHandleCtrlC.test_scan_ctrl_c
w3af.core.ui.console.tests.test_scan_run.TestScanRunConsoleUI.test_two_scans
w3af.core.ui.tests.gui.auto_update.test_auto_update.TestAutoUpdate.test_disclaimer_shown_accept
w3af.core.ui.tests.gui.disclaimer_accept.test_disclaimer_accept.TestDisclaimer.test_disclaimer_not_shown
w3af.core.ui.tests.gui.disclaimer_accept.test_disclaimer_accept.TestDisclaimer.test_disclaimer_shown_accept
w3af.core.ui.tests.gui.disclaimer_accept.test_disclaimer_accept.TestDisclaimer.test_disclaimer_shown_not_accept
w3af.core.ui.tests.gui.encode_decode.test_encode_decode.TestEncodeDecode.test_decode_url
w3af.core.ui.tests.gui.encode_decode.test_encode_decode.TestEncodeDecode.test_encode_md5
w3af.core.ui.tests.gui.encode_decode.test_encode_decode.TestEncodeDecode.test_encode_url_default
w3af.core.ui.tests.gui.exploit.test_exploit.TestExploit.test_scan_exploit
w3af.core.ui.tests.gui.exploit_from_template.test_exploit_from_template.TestExploitFromTemplate.test_exploit
w3af.core.ui.tests.gui.export_request.test_export_request.TestExportRequest.test_export_request_python
w3af.core.ui.tests.gui.fuzzy_request_editor.test_fuzzy_request_editor.TestFuzzyRequestEditor.test_GET_request
w3af.core.ui.tests.gui.fuzzy_request_editor.test_fuzzy_request_editor.TestFuzzyRequestEditor.test_POST_request
w3af.core.ui.tests.gui.fuzzy_request_editor.test_fuzzy_request_editor.TestFuzzyRequestEditor.test_invalid_request
w3af.core.ui.tests.gui.fuzzy_request_editor.test_fuzzy_request_editor.TestFuzzyRequestEditor.test_offline_url
w3af.core.ui.tests.gui.invalid_target_url.test_invalid_url.TestInvalidURL.test_invalid_url
w3af.core.ui.tests.gui.invalid_target_url.test_invalid_url.TestInvalidURL.test_invalid_url_correct_mistake
w3af.core.ui.tests.gui.main_window.test_main_window.TestMainWindow.test_main_menu
w3af.core.ui.tests.gui.main_window.test_main_window.TestMainWindow.test_plugins_loaded
w3af.core.ui.tests.gui.main_window.test_main_window.TestMainWindow.test_profiles_loaded
w3af.core.ui.tests.gui.main_window.test_main_window.TestMainWindow.test_tab_navigation
w3af.core.ui.tests.gui.manual_requests.test_manual_requests.TestManualRequests.test_GET_request
w3af.core.ui.tests.gui.manual_requests.test_manual_requests.TestManualRequests.test_POST_request
w3af.core.ui.tests.gui.manual_requests.test_manual_requests.TestManualRequests.test_invalid_request
w3af.core.ui.tests.gui.manual_requests.test_manual_requests.TestManualRequests.test_offline_url
w3af.core.ui.tests.gui.new_profile.test_new_profile.TestNewProfile.test_new_profile
w3af.core.ui.tests.gui.no_plugins_scan.test_no_plugins_scan.TestNoPluginsScan.test_no_plugins_enabled
w3af.core.ui.tests.gui.profile_loading.test_profile_loading.TestProfileLoading.test_profile_loading
w3af.core.ui.tests.gui.proxy.test_proxy.TestProxy.test_basic_forwarding
w3af.core.ui.tests.gui.proxy.test_proxy.TestProxy.test_intercept
w3af.core.ui.tests.gui.request_help.test_request_help.TestRequestHelp.test_main_menu_help
w3af.core.ui.tests.gui.scan_offline_url.test_scan_offline_url.TestScanOfflineURL.test_scan_offline_url
w3af.core.ui.tests.gui.tools_menu.test_click_menu.ClickMenu.test_click_menu
w3af.core.ui.tests.gui.two_scans.test_two_scans.TestTwoScans.test_two_scans
w3af.core.ui.tests.wrappers.tests.test_xvfb_server.TestEnvironment.test_get_screenshot
w3af.core.ui.tests.wrappers.tests.test_xvfb_server.TestEnvironment.test_get_screenshot_not_started
w3af.core.ui.tests.wrappers.tests.test_xvfb_server.TestEnvironment.test_not_running
w3af.core.ui.tests.wrappers.tests.test_xvfb_server.TestEnvironment.test_run_hello_world_in_xvfb
w3af.core.ui.tests.wrappers.tests.test_xvfb_server.TestEnvironment.test_run_with_stopped_xvfb
w3af.core.ui.tests.wrappers.tests.test_xvfb_server.TestEnvironment.test_start
w3af.core.ui.tests.wrappers.tests.test_xvfb_server.TestEnvironment.test_start_start
w3af.core.ui.tests.wrappers.tests.test_xvfb_server.TestEnvironment.test_start_vnc_server
w3af.core.ui.tests.wrappers.tests.test_xvfb_server.TestEnvironment.test_stop_not_started
w3af.core.ui.tests.wrappers.tests.test_xvfb_server.TestEnvironment.test_two_servers
w3af.core.ui.tests.wrappers.tests.test_xvfb_server.TestEnvironment.test_verify_xvfb_installed_false_1
w3af.core.ui.tests.wrappers.tests.test_xvfb_server.TestEnvironment.test_verify_xvfb_installed_false_2
w3af.core.ui.tests.wrappers.tests.test_xvfb_server.TestEnvironment.test_verify_xvfb_installed_true