Add conditional dependencies for py26

Didn't want to do this, but I don't see a clean
alternative. If we're on python2.6 we install
ordereddict and simplejson.

I went through and ensured all json imports use
'from botocore.compat import json'.

Also updated the part in the data loading process
that checks for python2.6 and uses the non ordered
dictionary json loads call.

Fixes #51.

Not opposed to a cleaner alternative.