Allow controlling dev dashboard version with environ variable.
Allow controlling dev dashboard version with environ variable.

Currently, the dashboard/bin/deploy script always automatically computes a dev
version from the git commit. However, sometimes it's more convenient to be able
to deploy to a particular dev version.
This CL allows specifying the version using an environment variable:
VERSION=dev-benjhayden-7777777 ./dashboard/bin/deploy
The environment variable is optional. If unspecified, the existing behavior
using the git commit is used.

Change-Id: Ib6cc915c47027cbbda48e3e638eabf8542374d0b
Reviewed-on: https://chromium-review.googlesource.com/1093263
Reviewed-by: Simon Hatch <490a224d89645d3fea983d7189ce51bde0a00c1d@chromium.org>
Commit-Queue: Ben Hayden <d3ffe0e065c2328e497bb32a07f4dcb29138ef5b@chromium.org>

catapult-project/catapult,catapult-project/catapult,catapult-project/catapult,catapult-project/catapult,catapult-project/catapult,catapult-project/catapult,catapult-project/catapult