Only render doc page breadcrumbs as needed

All routes changes used to cause the breadcrumbs to be re-rendered,
even though they often don't change. This small change checks to see
if the crumbs have in fact changed, and only re-renders if so.

Closes COUCHDB-2465
Global notifications now full width

This makes a small change to the global notifications so that it goes
full page width. This was done partly to solve the missing close "x"
that was getting put off screen, but also because it just looks better
this way.

Closes COUCHDB-2473
Cleanup: remove unused index.html

I first noticed an unused footer element, but it turned out that
the whole `index.html` file was unused (it is now generated by
`index.underscore`)
Replace .execute() for .click() behavior in Nightwatch tests
Cleanup: Remove unused nv.d3

stats are removed now and we don't use it any more

Closes COUCHDB-2355
New design for docs

Port from #33:

Based on the work of Jenn Schiffer <jenn@pancaketheorem.com>
(@jennschiffer), Sue Lockwood <deathbear@apache.org>
(@deathbearbrown) and Sean Barclay (@seanbarclay)
Fix the flash on doc page route changes

This is subtle and only occurs on Chrome. To reproduce:
1. Go to the Database -> All Docs page for a database.
2. Click from the All Documents page to All Design Docs.

Click back and forth a few times. Notice that sometimes there's a
sort of quick flash that appears over the breadcrumbs section making
it look a little like the breadcrumbs are being re-rendered.

Closes COUCHDB-2467
Nightwatch test to test lookahead component