match license with readme (+or later)

I asked for this 7 month ago #5 I now see that you have it in the readme.txt and the latest change was 9 month ago? So you even had this b4 I asked? Anyway you might want to mach the main php file to not confuse people like me ;)
Merge pull request #10 from nextgenthemes/master

match license with readme (+or later)