Removes left/right pseudo selector recognition

These are normally intended as properties.
Reverse checks for safer code path

Check first for valid result before using it!
Updates README.md for perl-libsass transition to sass org
MIT License

In order to fully integrate this into libsass, we need it to be a compatible license. That, or you can just re-assign copyright and we'll take it from there.
Merge pull request #15 from hcatlin/master

MIT License
Merge remote-tracking branch 'upstream/master'