Display metadata edit dialog
Dialog content transitions

* Implements fade(In/Out) transitions when switching
between view and edit/add mode
Metadata edit form

* Added a template for the form to be displayed when
a user wants to add a new metadata item via the edit
metadata dialog

* TODO: The template for adding place metadata
Add Drops API class

* Added stubs for the Drops API class

* Added SwiftRiver_Client#get_drops_api() to get and
return the Drops API
Add drop service class

* The drops service class invokes drop-related API requests
on behalf of the drop controllers
Prevent event propagation on delete metadata

* When a metadata item is deleted from the listing, we
have to stop/prevent event propagation else the dialog
will transition into edit mode.
Implement "View full-screen"

* Event wiring for "View full-screen" button.  Though the event
handler is in place, registration of the click event for this button
has been disabled mainly because once in "full screen mode"
there is no way to navigate back to the drops view/listing
Generate CSRF token once per session

* Regenerating the token during each time token validation
is performed causes DOS. E.g. A user being unable to use
separate browser tabs for form submission
Implement sharing dialog

* Implemented the dialog for sharing drops. Twitter and Facebook
sharing are still performed as before i.e. a pop up window loads
the login page for the selected service before the user can proceed
with sharing

* For email sharing, the share dialog transitions to "email sharing" mode
where the user enters the CAPTCHA and recipient's email address.
Stubs for drop comments API resources
Update metadata template

* Removed the "+" icon from "edit-metadata-item-field-template"
because only a single item (metadata) can be added a time.

* Add parentheses to the display label when it's length is > 50
chars
Merge remote-tracking branch 'origin/rivers-ui-dev' into buckets-ui-dev

Conflicts:
	themes/default/media/js/global.js
Support for PUT and DELETE API requests

* For PUT and DELETE requests, the request body is
encoded to JSON by default and the content type for the
request header is set to "application/json;charset=UTF-8"
Drop comments and links

* Implemented creation of new links via the "Edit" modal
dialog when the drop detail dialog is open

* Commenting on drops from the drop detail view
Simultaneous update of metadata views

* When a metadata item is added/deleted, the side listing
on the drop's full view is updated and so is the counter next
to the "gear" icon
Add drop tags

* Implemented adding of tags - with a drop down to select the tag
type - via the dialog used for editing a drop's metadata
Implement "Add to Bucket" modal

* Drops can now be added and removed via the "Add to Bucket"
modal with the bucket count updating on the UI simultaneously
Create Bucket

* Creation of buckets via the buckets headers view
and "Add to Bucket" modals. The bucket lists in both modal
view are updated simultaneously
Merge branch 'ui-dev' into buckets-ui-dev
Implement bucket settings

* The bucket name and display settings of the bucket are now
modifiable via the settings page. Changing the name of the bucket
triggers a redirect to the settings page using the URL slug generated
from the new bucket name