SideBySide2: Fix max width of comment widget groups

The group should have a max-width of 650px. This allows the group
to show the right side drop shadow on a normally sized window,
making the comment appear to float a bit on the page.

The max width was incorrectly applied to the header line of the
comment, andwas not being used by the browser to size the group.

Change-Id: I564c7fd9b154d64cdf1b20836351f40954a4900d
ChangeScreen2: Support [/] keys to navigate files in a cycle

When viewing the last file pressing ] takes the user up to the
change screen. Allow [ to return them to the last file, much as [
is an undo for an accidental ] between files.

Likewise allow ] to enter into the commit message.

Change-Id: Id1fac2cb0a34ecd87f2526400019bd65bd294186
Move change id and status to left side of ChangeScreen2

Some users have reported missing the subject line and only reading
the commit message body on ChangeScreen2.  The subject is bold and on
a "trimColor" (e.g. grey) background while the message body is on the
page background color (e.g. white).  This coloring makes the subject
appear to be unrelated to the message, and reviewers find themselves
missing important context when trying to understand the commit.

Move the subject line down into the commit message body area and
slide the change number and status into the left 1/3rd of header
line bar.

Change-Id: I61c3143c636e234776189d545def9ff528eaa2bf
Make even more CSS external

GWT's class obfuscation makes it impossible for users to write
their own CSS that won't break on upgrade. This further helps preserve
class names so uses can continue to rely on the names and use
GerritSite.css to it full ability.
Replace favicon with aokp icon
add gravatar to core plugins
Update Icons