Existable.login_from_author_pattern(text) when text is nil

See Gist for Error: https://gist.github.com/superscott/44d428e1b0ab6d6b0759
Just added Nil check before proceeding, and added additional test for when Text is nil.

OSX: 10.9.4
Ruby: ruby 2.1.2p95 (2014-05-08 revision 45877) [x86_64-darwin13.0]
RVM: Yes.