Enforce SDK-Robot SW version checks for all Exs

Corresponding changes to new version check call in RobotEnable
of baxter_interface. Will fail on version mismatch for all
'standard' Rethink programs, but default value otherwise is False.

See baxter_interface commit for more information.
Enforce gripper version check on electric for Exs

All examples now default to enforcing a gripper version check
on electric grippers. Corresponds to new version check addition in
baxter_interface.
Updates per review #23

Import ordering
Merge pull request #23 from RethinkRobotics/version_checks

Enforce SDK-Robot SW version checks for all Exs