Bug 29282: (QA follow-up) Class consistency

Bug 29282: (QA follow-up) Class consistency

This patch updates the field classes introduced in this patchset to
improve class name consistency.  We remove the _field apendment and to
repvent a clash we update the existing 'renewals' class elsewhere to
'renewals-info' to more clearly reflect it's content.

Test plan
1) The patchset should continue to function as described in prior patches
2) Build the CSS for the staff client
3) Check the 'Checkouts' table on various screens and confirm the
   renewals information still displays as it always has in the table.

Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>