Add short git revision to 'topaz -v'.

Moved fetching of git revision to module-level.

Strip newline from GIT_REV and add to space.

Fixed tests to align with addition of revision.

GIT_REV ~> TOPAZ_GIT_REV

TOPAZ_GIT_REV ~> RUBY_REVISION

RUBY_REVISION ~> TOPAZ_REVISION

TOPAZ_REVISION exposed on the Topaz module instead of Object.

Back to RUBY_REVISION