Lusitanian/PHPoAuthLib — pull request #284 by BlaM (2014-07-28 12:00:54+00:00)
Title: Added PLAINTEXT signature algorithm

I had to access a https based webservice that does not accept any of the HMAC-SHA1 signatures - even though it claims to support them. In the end I switched to PLAINTEXT signature, but I had to add support for that in your signature class.

http://oauth.net/core/1.0/#anchor22

Here is the simple implementation of that in your library.