JSON load/dump issue on Rails 3.1

[thhermansen]

We have a small issue with MassiveRecord and Rails 3.1 (well, ActiveSupport::JSON that is). In the 3.0 series the JSON decoder used a YAML backend as default. Meaning that we could ask it to decode "1" and it would return the Fixnum 1. This no longer works as ActiveSupport::JSON now by default uses the JSON gem. It seems to be a bit stricter, and will not decode the "1" into a Fixnum.

So, we'll need to change our load/dump strategy a bit and make it a bit smarter not running simple types like fixnum via the coder.

[thhermansen]

Maybe #80 can help this issue.