Address several issues raised on Github

* add alias for Special:Hoststats
  issue 6 at https://github.com/Hydriz/HostStats/issues/6

* add hoststats permission
  issue 7 at https://github.com/Hydriz/HostStats/issues/7

* fix licensing information
  issue 8 at https://github.com/Hydriz/HostStats/issues/8

Change-Id: I2cffddcf889f18f7bf7156c1368eb672c71c3196