Crop widget

WIP
Fix jCrop style (add image)
Fix crop widget usage example
Crop widget refactoring
typo
Accept all falsy values as "not set" for size options in crop widget
fix in crop widget
include crop widget's styles on sass side
double underscores for private members in crop widget
move crop widget to ui directory
Merge branch 'master' into crop

# By Dimitry Solovyov
# Via Dimitry Solovyov
* master:
  Use pluralization for current locale only
  Comment on pluralization rules
  Rails-like pluralization nouns
  Latvian locale
  Shorter file button title
  Locale overrides
  Pluralizable messages
  Pass current lang to social iframes
  Moved l10n from locale/locale to locale
  Localized templates
  Default locale fallback
  Require all added translations
move crop widget template to /templates
changes in crop widget's error handling
some changes in crop widget
refactor crop widget

also proper destroy()
some docs on crop widget
proper getCurrentCoords() in crop widget
Crop widget: some refactoring and fixes
change CDN API
rework crop widget