New methods! More accuracy! \o

* Let's not rely on CURL guessing the MIME type anymore. It is always
application/octet-stream.
* Now uses /ph/settings instead of /bq/settings.
* New methods updatePhoneNumber, updatePhoneNumberPrivacy,
updateFeatureSettings and setNumBestFriends.
* Fixed bug where SnapchatAgent::request would return FALSE instead of
empty string if the response was empty.