As discussed, flatten the oauth code
The OAuth/OAuthHeaderGenerator was only used in one place
And copies data into OAuthHeaderData in order to then copy it into the crenna OAuthRequest
Testing the results of oauth header generation is almost as easy as the RequestBuilder now just returns data
so the tests are still there in RequestBuilderOAuthHeaderTests
Merge pull request #136 from AnthonySteele/FlattenOauthCode

As discussed, flatten the oauth code