add account/update_profile_banner api call

Author: Dimitri

account.go

@@ -21,3 +21,14 @@ func (a TwitterApi) GetSelf(v url.Values) (u User, err error) {
 	a.queryQueue <- query{a.baseUrl + "/account/verify_credentials.json", v, &u, _GET, response_ch}
 	return u, (<-response_ch).err
 }
+
+func (a TwitterApi) AccountUpdateProfileBanner(base64String string, v url.Values) error {
+	v = cleanValues(v)
+	v.Set("banner", base64String)
+
+	var emptyResponse interface{}
+
+	response_ch := make(chan response)
+	a.queryQueue <- query{a.baseUrl + "/account/update_profile_banner.json", v, &emptyResponse, _POST, response_ch}
+	return (<-response_ch).err
+}