Fixed typos
Merge pull request #97 from pborreli/typos

Fixed typos
unclobbering id builtin

1. removed refs to id builtin in favor of id_
2. style changes
- removing trailing whitespace
- adding extra line (coding style)
3. using params.pop instead of params.get
- prevent id key from residing in params
- avoid overriding id builtin
- allow backwards compatibility; id, id_
4. adding APIResource compatibility integration test
5. Testing ListObject.retrieve with None values for id/id_
6. removing TypeError check