Extract split_on_commas into a utils module
Promote top level args to put-metric-data
Rename renames test to utils
Add util code for validating mutex groups
Fix --no-paginate to check for None values

Basically --no-paginate didn't work.  If you don't check for None
values, the arg object will insert args that don't actually exist in the
op model which botocore will (correctly) complain about.

Added an integration test as well as a unit test to catch this
in the future.
Merge branch 'fix-no-paginate-arg' into develop

* fix-no-paginate-arg:
  Fix --no-paginate to check for None values
Add comment about default value

As per review feedback.
Merge branch 'put-metric-data' into develop

* put-metric-data:
  Add comment about default value
  Add util code for validating mutex groups
  Rename renames test to utils
  Promote top level args to put-metric-data
  Extract split_on_commas into a utils module