Minor refactoring
check if PP can work on current page on page' loading event.
1) check if url is "chrome://*"; 2) check if url is "file://*" and if access to file scheme is allowed
Refactored content script execution
Adding controller (in progress)
Merge branch 'release/1.22' into develop
Merge branch 'feature/check-if-pp-can-work-on-current-page' of https://github.com/kroleg/perfectpixel into kroleg-feature/check-if-pp-can-work-on-current-page
Spelling
Fixed js loading
Migrating to backbone.js
Restoring features
Enable/disable buttons
Restored UI events (mostly)
Restored panel double-click functionality
Restored Drag'n'Drop
Refactored panel rendering
Minor fixes
Restored keydown, minor fixes
Restored overlay selection
Restored localStorage support
Cleanup