GUI-1207: Revamped sharing panel for bucket/object details page

Implements the redesigned sharing panel for https://eucalyptus.atlassian.net/browse/GUI-1207

Note that GUI-1207 was branched from GUI-1209, so https://github.com/eucalyptus/eucaconsole/pull/921 should be merged prior to reviewing this pull request.
Didn't the checkbox argument get factored out already?