Adds a Package Settings Menu with links to readme, license, etc
Adds command palette: run tests and open preferences commands
Adds a setting to enable/disable running tests. Disabled by default. The reason is that previously Vintageous overrides the users F5 and Ctrl+F5 keymaps because the keymaps, which are only useful while developing, were always enabled. The command palette run test commands don't need the setting enabled, so tests can always be run from the command palette. To use the keymaps, this new setting needs to be enabled.
Moved development related keymap file into the tests/ directory with a view to later add a .gitattributes file that will export-ignore dev related files, commands, etc. so that they are not installed when Vintageous is installed by package control.