Audit and convert tests to test/unit (minitest)

:construction: WIP :construction: 

This PR converts the RSpec tests to minitest. Most of the tests were translated over, but I'll make inline notes where I modified or removed tests for clarity.

- convert rspec tests to test/unit
- rename 'test/common' to 'test/test_helper'
- remove metaid dependency
- remove rspec dependency
- remove autotest
- auto generate gemspec files manifest

I'd like to rebuild this test to use a real socket instead of a pipe since this is why JRuby CI builds fail (mismatch between pipe and socket; *thanks strong Java types/Obama*). If this is passing as is, let's worry about replacing the mock and pipe later, and I'll assign myself to that.