(maint) Re-Allow an array of hosts in apply_manifest_on

Before it was refactored, apply_manifest_on allowed an array of
hosts. The Puppet acceptance tests rely on this behavior, so we need
to re-introduce it.
Merge pull request #136 from branan/apply_manifest_on_array

(maint) Re-Allow an array of hosts in apply_manifest_on
Merge pull request #137 from anodelman/make-gem

create beaker 1.6.2 gem
google cloud integration