Correct the creation of the hand frames.

The rightHand info was always the identity matrix.
Directly use the getHandParameter and remove
unnecessary intermediate operations.
Add leftGripper and rightGripper, aliases for the hands. Fixes #5

More REP120-friendly.
Correct typo.
Merge pull request #6 from francois-keith/master

Add gripper frames and correct the initialization of the hand frames