Move rspec dependency from Appraisals to Gemfile

This way when running a single test file in development we can say `rspec ...`
or `spec ...` instead of having to prepend it with BUNDLE_GEMFILE=...
Remove Gemfile.lock

Now that certain dependencies in Gemfile are dependent on the current Ruby
version we can no longer keep the lockfile in version control.
WIP: Fix suites.yml so it finds formatter path
WIP: Better way to write this
WIP: Update Travis config