[baxter_sim_hardware] modify default value of electric gripper false

[knorth55]

electric gripper value should be standardized to false, according to baxter_sim_kinematics and version 0.9 or older https://github.com/RethinkRobotics/baxter_simulator/blob/master/baxter_sim_kinematics/launch/baxter_sim_kinematics.launch#L5-L6

[knorth55]

@IanTheEngineer ping

[IanTheEngineer]

The major addition of the 1.2 release was that the electric end-effectors (an often requested feature) was added to the simulator. So, by default because Baxter is more useful with an end effector, and since we've now crossed the 1.0 threshold, it seems sensible to keep end effector by default.

[knorth55]

@IanTheEngineer Thank you for your response. Following 1.2 version, i will close this PR and make another PR to modify default value of lines below false. https://github.com/RethinkRobotics/baxter_simulator/blob/master/baxter_sim_kinematics/launch/baxter_sim_kinematics.launch#L6-L7