URLENC response entity parsing fails when content-type is not application/x-www-form-urlencoded

URLENC parsing is done via URLEncodedUtils. Unfortunately, that method has a test to verify the content-type before parsing the data. HTTPBuilder already tests for the content-type, but wants to allow manually parsing a response even if the content-type is wrong (as in the case of Twitter's OAuth response.) So I need to fake a content-type if the response has it wrong.

See: http://hc.apache.org/httpcomponents-client/httpclient/xref/org/apache/http/client/utils/URLEncodedUtils.html#117