First pass at customizable upstream session.

I've got this working with a subset of our real performance tests, still
needs UI work and further testing.
remove ClientDevice
kick travis
Merge branch 'master' into generic_upstream_session
oops, remove byebug from the gemfile
remove unused test scaffolding
Merge pull request #2 from cloudcity/generic_upstream_session

Replace ClientDevice with UpstreamSession