Renamed LighttpdCGIRootFix to simply CGIRootFix

  - It is easier to spell. Seriously.
  - The problem is not limited to Lighttpd (See mitsuhiko/flask#680)
  - I added a parameter to specify a custom app root. This is the change
    i am a bit unsure about.
Merge pull request #266 from untitaker/cgi_root_fixer

Renamed LighttpdCGIRootFix to simply CGIRootFix