MNT: Enhanced documentation of recip.process_to_q

- Exposed the frame_mode variable as an input parameter to
  recip.process_to_q
- Added new tests to make sure that bad entries for frame_mode
  actually fail and that good entries do not raise an exception
DOC: Added optional flag to optional param
MNT: Fixed and tersified re Caswell's suggestions
DOC: Removed bad docs re caswell
MNT : minor style/pep changes
TST : fixed recip tests

 - split up the exception tests from main tests
 - turns out the validation works on py3k
Merge pull request #2 from tacaswell/recip

Looks good, thanks!
Merge pull request #137 from ericdill/recip

Rewrite of documentation for recip.process_to_q