Keyboard navigation from change screen into diffs

The support for keyboard navigation in the change screen allows
the user to start reviewing the files that were changed within the
different patch sets by just using keys.

Bug: issue 498
Change-Id: I577f0a2d5b6da20d48b5cf80035c2571ee903ebb
Signed-off-by: Edwin Kempin <edwin.kempin@gmail.com>
7 files changed