GUI-1207: Bucket and object detail pages

Implements the following for https://eucalyptus.atlassian.net/browse/GUI-1207 …

- Bucket details page
- Object details page
- Add "Download" link to object details page (and bucket contents page)
- Sharing panel (ACL) editor for bucket and object details page
- Metadata editor for object details page
- Allow object rename on the object details page
- Disable the "Add Metadata Pair", and "Add Account" buttons until changes are made in the respective panel
- Disabled the "Save Changes" button until changes are made on the page
- Display a warning when navigating away from the page when there are unsaved changes (e.g. when an ACL or metadata item has been added/removed).

The lifecycle rules editor has been punted to a later pull request.

Note that the metadata editor on Eucalyptus isn't fully functional due to EUCA-9948.  We're tracking the metadata editor component for Eucalyptus in GUI-1254
Yep, as I showed in the demo, the link returns an access denied error on Eucalyptus.  I don't know if there are policies or ACLs at work there, but the generate_url() method works fine on AWS.  I'm open to suggestions on the Euca side.