Update getIdentity() method to getInstance()

Update handler for changes made in this commit: https://github.com/cartalyst/cart/commit/7fec9343f7fdfe0832b05a6986bc5001de0ccf11
Update getIdentity() method to getInstance()

Update handler for changes made in this commit: https://github.com/cartalyst/cart/commit/7fec9343f7fdfe0832b05a6986bc5001de0ccf11
Merge pull request #5 from travisulrich/patch-1

Update getIdentity() method to getInstance()