Added getter/setter utils.js methods for local storage

This is primarily proactive; there are only a couple of places in the code
that use local storage, but I wanted to nip it in the bud now and use
helpers instead.

Closes COUCHDB-2432
Moved Add Section button on Config page to header.

Closes COUCHDB-2421
Fixes back button from edit document

Closes COUCHDB-2427
Fix for page body widths being incorrect on Stats #2

This is the second version of this ticket that doesn't contain
whitespace fixes.

As noted in the ticket, the widths of the main body of the Stats
and Accounts page were incorrect. On the stats page, the rightmost
column was offscreen; on the Accounts page the text gets cut off.

This ticket fixes the stats page. The Create Admins page still
has the text get cut off. This is unrelated to this issue - I'll
fix that in a separate ticket (COUCHDB-2417).

Closes COUCHDB-2428
Account page style and usability fixes

This ticket is a general style clean-up of the Accounts page. Namely:

- general CSS style fixes
- sidebar styles now consistent with other pages in app
- focus is placed on first text box on page when page load (N.B.
autofocus wouldn’t work consistently, hence the JS)
- "Databases" left nav item no longer selected

*** Please note: the Create Admins page is still having it's text cut
off. This will be fixed once PR #123 has been merged. ***

Closes COUCHDB-2417
Fix for API Urls on Stats, Config and Replication pages

Closes COUCHDB-2439