Update share action text to display owner/recipients

- when a share was changed, update the share action text
- added file data attribute "data-share-recipients"
Added unit tests for share.js and share icon
change shared folder icon to use share icon instead of people
More unit tests and fixes for share
Now using shareOwner for the share owner

Makes it consistent with the regular file list fileData
let file cache handle the versions size
return size '0' if the trashbin folder doesn't exists yet
use OC_DB::dropTable()
minimal mail template editor for administrators, refs #7177
Multiple fixes to sharing overview

- scrolling to next page now correctly renders share icons
- reshareing/unsharing a reshare will now still keep "Shared by" label
convert mail template editor to app framework for a restful api
Fix merge conflict
Use recipient display names when updating shares in the UI

Since OC.Share didn't have any array containing the list of shares for
the current file, OC.Share.currentShares has been introduced to contain
the full share item structure instead of the reduced one
OC.Share.itemShares.

The event "sharesChanged" is now passing OC.Share.currentShares, which
itself includes the display name to be displayed for the recipients in
the action icon.
Do not update action icon recipients for file list

Since the files app doesn't have the recipient information on load it
cannot initially render the recipients in the action icons.

For this reason the action icon will not be updated with the recipients
after changing the shares, for consistency.
Upgrade SabreDAV to 1.8.10
Updating SabreDAV namespaces
fixes during test
explicit position:relative for app-content, fixes first run layout
remove obsolete position rule from files app
Merge pull request #8875 from owncloud/app-css-relative

explicit position:relative for app-content, fixes first run layout
Merge pull request #8791 from owncloud/share-overview-sharewithstatus

Update share action text to display owner/recipients