Various Layout Fixes for Sharing Dropdown.

Fix for https://github.com/owncloud/core/issues/1750 and with https://github.com/owncloud/core/issues/895. 
PR contains the following changes : 
1. The Share With sentence doesn't go out of the box.
2. The unshare button on hovering doesn't make the CRUDS layout change.
3. The Email button gets a better layout.
4. The Email Input is made wider to sync with other Inputs.