Use specified capitalization in Marketo API calls.

- Automatic translation is correct for *most* Marketo API request
  parameter fields, but not all. Ensure that the request objects are
  created properly. Resolves #15.
Removing dead tests.
Fixing test/build issues.

- Chasing the rbx moving target. Again.
- Ruby 1.9.2 (MRI) will no longer be tested on Travis.
Merge pull request #16 from ClearFit/fix-automatic-request-conversion

Use specified capitalization in Marketo API calls.