Update BOSH gem

The previous version referred to a gem that is no longer available.

Signed-off-by: Mark Rushakoff <mrushakoff@pivotallabs.com>
Bump src/tests

Bump cloudfoundry/vcap-yeti:
  Dave Liebreich:
     bump ruby version ( Travis Unknown )
  Johannes Tuchscherer:
     Updating the gcf binaries ( Travis Unknown )