replace jquery-json with es5 equivalents

[bcm]

fixes #3

[dchelimsky]

Thanks @bcm. Do you think, for the case in which the developer fails to require json2, there should be an explicit warning for the potential end-user (who doesn't know anything about javascript)? i.e. test for the existence of JSON and if it's not there alert the user to upgrade his/her browser?

[bcm]

I think that choice is best left to the application developer. I'm sure different people will want to handle that situation in different ways.

[dchelimsky]

Merged: 7f3d70c