Memory leak when exitting dynamixel_workbench_controllers

[pazeshun]

Currently, when we kill dynamixel_workbench_controllers with Ctrl-C, the motors are left torque on.
However, I think this is due to a bug of dynamixel_workbench_controllers.

Expected behavior is making the motors torque off:

dynamixel-workbench/dynamixel_workbench_toolbox/src/dynamixel_workbench_toolbox/dynamixel_driver.cpp

Lines 29 to 37 in 67a1631

	DynamixelDriver::~DynamixelDriver()
	{
	for (int i = 0; i < tools_cnt_; i++)
	{
	for (int j = 0; j < tools_[i].getDynamixelCount(); j++)
	{
	writeRegister(tools_[i].getID()[j], "Torque_Enable", (uint8_t)0);
	}
	}

But this destructor is not called because dxl_wb_ (pointer to instance of DynamixelWorkbench (child class of DynamixelDriver)) is a bare pointer:

dynamixel-workbench/dynamixel_workbench_controllers/include/dynamixel_workbench_controllers/dynamixel_workbench_controllers.h

Line 75 in 67a1631

DynamixelWorkbench *dxl_wb_;

dynamixel-workbench/dynamixel_workbench_controllers/src/dynamixel_workbench_controllers.cpp

Line 45 in 67a1631

dxl_wb_ = new DynamixelWorkbench;

and current code does not call delete against that pointer.
This causes a memory leak.

Although this seems a bug, many people probably depends on the current behavior and that memory leak is not fatal to the PC.
So I just leave this issue without fixing it.

Related to #386