Proactively format options to conform to the standard used internally

(i.e: hash with all keys as symbols). Internally, all options are retrieved as symbols, and since some services conform to the API, but do not uniformly convert all options to symbols before sending to Addressable, let's be proactive in formatting. 

Ref: https://github.com/google/signet/pull/40

Tests passing in:

**MRI**
- 1.9.3
- 2.0.0
- 2.1.0

**JRuby**
- 1.7.11 in 2.0 mode