Add MPL 2.0 License

Added Mozilla Puplic License 2.0.

See http://www.tldrlegal.com/license/mozilla-public-license-2.0-%28mpl-2%29 for a good summary of the license

This license is a good fit for this project because unlike strong copyleft licenses, code under the MPL may be combined with files under any license in a "larger work", so long as conditions for the MPL are still met for "covered" components. See http://en.wikipedia.org/wiki/Mozilla_Public_License for more details