PID segment cleanup and specs.
spec for PID (in particular the patient name) , remove idx from segment definition(supplied idx was buggy), added missing fields.
Require files in gemspec via git, upgrade Rake dep.

The minimum rake requirement should be at least version 10.0.0 as
there are some security issues associated with the earlier versions.

Nobody has time to list files by hand in the gemspec. I'm pretty
sure there is an open PR about this, that just goes and modifies
the list by hand.
Update the travis badges for our fork.
Remove support for RBX.

It's no longer supported on TravisCI, no one uses it anyways.
Add some new rubies to the mix as well.
MSH segment cleanup and specs.
spec for msh, remove idx from segment definition, added missing fields, remove convert_to_ts (use superclass)
Add some rbx love back in.

Because some people use it and it's not that difficult.
Fix PID field indexes

The indexes for the PID were off by such that if you tried to call
a field like patient_dob you would get the value for previous element.

This commit fixes this issue and adds a full test for all values of a PID.