Clarifying License Type

The original BSD license isn't compatible with the GPL license that I use with WordPress plugins but the revised BSD license you have in `LICENSE.md` [*is* compatible](http://en.wikipedia.org/wiki/BSD_licenses#3-clause_license_.28.22Revised_BSD_License.22.2C_.22New_BSD_License.22.2C_or_.22Modified_BSD_License.22.29). I wanted to clarify for future users who want to include this in their projects and need to know exactly which license you're using.