DAR-2884, fix wiki nav preview being cut off for long dropdowns
removed oasis-navigation-v2-validation-caption message and its usages
DAR-3125: fixed issue with hovering on menu items; the event was fired twice
DAR-3132 fix proposal
Merge branch 'dev' into DAR-2884

Conflicts:
	extensions/wikia/EditPageLayout/css/EditPageLayout.scss
	extensions/wikia/EditPreview/js/preview.js
Merge pull request #2210 from Wikia/DAR-2884

DAR-2884, fix wiki nav preview being cut off for long dropdowns