GPL 2 license addition

Just so I know edits are kosher.  If any changes or seconds thoughts
please dismiss this and any subsequent.  Also please know that this
addition is a request only and as with any request can be nullified.
Merge branch 'master' of github.com:taylorchu/powerdown into gpl2-license
Merge pull request #13 from Gen2ly/gpl2-license

Gpl2 license