Rename HttpClient to HttpClientWrapper
The name "HttpClient" causes complexities
as it clashes with the class System.Net.Http.HttpClient (new in .Net 4.5)
Which this will eventually be a wrapper of.
Merge pull request #53 from AnthonySteele/master

ForAffiliatePartner  extension method
Merge pull request #60 from AnthonySteele/httprename

Rename HttpClient to HttpClientWrapper
ISSUE-61: Change to UrlEncode oath_token using OAuthBase capitalising UrlEncode method and added a test
Merge pull request #62 from gregsochanik/invalid-token-on-post

Change to UrlEncode oath_token using OAuthBase capitalising UrlEncode method and added unit test