enhance code base, delete unused code and fix some bugs

[mfuentesg]

• Use package_control command advanced_install_package
• Avoid file replacements before finishing installation
• Add pipeenv as package manager
• Delete unneccessary code
• Improve gist api lib (unit testing)
• Replace location of logs and current version reference
• Use builtin logger instead of custom logger
• Delete custom popups in favor to builtin dialogs
• Fix invalid exceptions
• Download/Get gist without token (unneccessary)
• Exclude Sync Settings.sublime-settings file from everywhere
• Deprecate custom patterns for file selection in favor of bash wilcards
• Fix enconding errors on file reading
• Simplify files filtering

[codecov-io]

Codecov Report

:exclamation: No coverage uploaded for pull request base (master@973a2b9). Click here to learn what that means. The diff coverage is 93.85%.

@@           Coverage Diff            @@
##             master    #107   +/-   ##
========================================
  Coverage          ?   93.9%           
========================================
  Files             ?      13           
  Lines             ?     541           
  Branches          ?       0           
========================================
  Hits              ?     508           
  Misses            ?      33           
  Partials          ?       0

Impacted Files	Coverage Δ
tests/test_settings.py	100% <100%> (ø)
sync_settings/libs/logger.py	100% <100%> (ø)
sync_settings/libs/path.py	100% <100%> (ø)
tests/__init__.py	100% <100%> (ø)
tests/test_path.py	100% <100%> (ø)
sync_settings/libs/gist.py	100% <100%> (ø)
tests/test_gist_api.py	100% <100%> (ø)
tests/test_sync_manager.py	100% <100%> (ø)
sync_settings/libs/settings.py	100% <100%> (ø)
tests/test_sync_version.py	100% <100%> (ø)
... and 3 more

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