CMS-1056 Content Manager - Drag n drop Form item set look and feel

Fix Sortable.js to work with new Form Item Set component, adding styles for new drop indicator.
Merge branch 'master' of github.com:enonic/wem-ce into CMS-1056

Conflicts:
	modules/wem-webapp/src/main/webapp/admin/resources/lib/ext/resources/css/admin.css
Merge pull request #151 from enonic/CMS-1056

CMS-1056 Content Manager - Drag n drop Form item set look and feel