Don't include system test gems when doing lint
Don't include system test gems when doing lint

The system tests gems (which right now are
beaker, beaker-rspec, & serverspec) include many dependencies that add
weight and time to the bundle installation. If any system test gems are
not needed for the lint builder job, then they can be added to the
bundler group "system_tests" and will not be installed as part of the
lint run.

This is also how Puppet Labs configures their modules' Gemfiles.

Change-Id: I19239d6ca451515bd0d51f167e5984fd8f31d793

openstack-infra/project-config,noorul/os-project-config,Tesora/tesora-project-config,noorul/os-project-config,dongwenjuan/project-config,dongwenjuan/project-config,openstack-infra/project-config,Tesora/tesora-project-config,coolsvap/project-config,coolsvap/project-config,anbangr/osci-project-config,anbangr/osci-project-config