rename variables and methods to match URI

- protocol -> scheme
- uri -> path
- param -> key
etc
pep8
Merge pull request #13 from kissmetrics/naming

Use proper URI naming conventions and follow PEP8
Resolved conflicts for `naming` changes & refined docs for constants.
Edited for consistency with `client_compat` docstrings.
Provided docstrings for compatibility client.
Documented create_query arguments.