Missing "patent grant" feature in AGPL

The AGPL license is missing the "patent grant" feature in the "permitted" category.

Unless I'm mistaken [section 11](http://www.gnu.org/licenses/agpl-3.0.html#section11) of the license is about granting patents licenses (it's the same text found in [GPLv3's section 11](http://www.gnu.org/licenses/gpl-3.0.html#section11)).
Merge pull request #197 from kappa7194/patch-1

Missing "patent grant" feature in AGPL