Added a Mongoid check
Added default Mongoid details to README
Added support for Mongoid 3 check

Also kept the Mongoid 2 check.
Made Mongoid's default check tied to v3.0
Added details to the README about default Mongoid checks
Merge remote-tracking branch 'rmm5t/mongoid' into mongoid

* rmm5t/mongoid:
  Added details to the README about default Mongoid checks
  Made Mongoid's default check tied to v3.0
  Added support for Mongoid 3 check
  Added default Mongoid details to README
  Added a Mongoid check
Adds mongoid check from rmm5t