Masonry fix.

* Removed margin around drops causing them to span multiple rows.
* Reduced the drop's width slightly.
Drops View: Display drop image
Display river and bucket lists in the header modal views.
Basic display of drops in river.

* Pending infinite scrolling and polling.
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