Upgrade to Ruby 2.0

No errors are issues found with this update. Ruby 2.0 does see some
improvement in performance.
Gemfile updated. Removed zurb-foundation version spec.

Updated gems to latest allowable version. Works well under Ruby 2.0.
Hash with indifference for site loader

The site loader still needs to enumerate sub entries as hashes. Use hash
with indifference instead of regular hashes.
Rbenv version set to 2.0.0-p247