FIX: When building URIs via Hash, Addressable expects URI#new and 

URI#parse to provide hash keys as symbols. One example of a little known occurrence where this would cause an issue is accessing the Google API via Google::APIClient::FileStorage, which stores and retrieves files as JSON - the keys of which are loaded in by the Google-Api-Client gem as strings. Here, we ensure that our options meet the format Addressable expects. The authorization/credential_uri= methods have been cleaned up a bit as well.

Specs pass on:

**MRI**
- 1.9.3
- 2.0.0
- 2.1.0

**JRuby**
- 1.7.11 in 2.0 mode