Trailing params for Rspec as well. Cleanup.

Adds support for trailing args also for Rspec, e.g.
`spins push spec/some_spec.rb -- --profile` will now send
`--profile` over the socket and pass to the test runner.

Included specs.
Switch force framework options. Preload RSpec only when determined.
Merge pull request #45 from rosic/test_unit_params

Passing trailing arguments to test runners