Bug fix (applies to master branch too): requestParams was being set in OauthPhirehose::getAuthorizationHeader(), even though already being set in Phirehose::connect(). When they get out of sync Twitter was returning a 401. Same for $url. The fix was to pass both $url and $requestParams to getAuthorizationHeader(). (The base class version of getAuthorizationHeader() simply ignores them.)
Also send oauth_version as "1.0A" instead of "1.0".
Throw exception if Phirehose class is being used instead of OauthPhirehose.