:smiling_imp: Let there be ... an IRestClientFactory!

- Added and implimented an IRestClientFactory.
- Refactored various lego pieces from an IRestClient to an IRestClientFactory.
- The 2x Providers now new up a new RestClient, when required. No more single instance per provider which was causing grief with the GoogleProvider. :satisfied:
- Updated NuGet packages and versions to 0.15.0.