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
Nightwatch test to test lookahead component