Update gwtorm to 1.8

Change-Id: Id65589a87b62b72a64cc8a7d80ea9bbf612950ef
SideBySide2: Center content in the browser window

The view runs at a fixed maxium width of 1484 pixels.  If the browser
window is wider than this width, center the view in the middle and
distribute the space evenly on either side.

Change-Id: I4c557c7a36e07a5b6ef9d4f2b725c0ea8d336a3f
Clarify in documentation that commentlinks are enabled by default

Change-Id: I63f31e1e6dfe9ed63ec677498904de3d86f6caea
Cache buck build results locally by default

Use buck-out/cache folder for local cache of buck build results.
Since we don't (yet) have a shared set of Cassandra cache nodes,
using a local cache is a good default. This will speed up build
times when switching between different version of Gerrit (for example
master/stable) and also when running "git bisect".

Change-Id: Id23c6053e7cb0498d129345f6ead18288d0e9701
Merge "SideBySide2: Center content in the browser window"
Merge "Cache buck build results locally by default"
Merge "Clarify in documentation that commentlinks are enabled by default"
Merge "Update gwtorm to 1.8"
Move "refs/..." constants to a RefNames class

This class lives in gerrit-reviewdb because "refs/changes/" needs to be
referenced from PatchSet in reviewdb/client (and other UI classes).

Rename constants to all use REFS_* instead of being inconsistent.

Change-Id: I76e6ee7e63a4549b51a43698fb50b54a19dabfc6
Remove unnecessary client dep from testutil

Change-Id: Ie118ec37d7b8f03fe234da2771b58290a6def43e
Consolidate parsing and formatting for label votes

We currently support two styles of parsing, Label-Value and
Label=Value. Consolidate these into a single LabelVote class.
(Unfortunately for backwards-compatibility reasons we can't just
eliminate Label=Value in ReviewCommand.)

Change-Id: I9e5255b184d786226e6b11fe059001608c00673d