Tests: Add a possibility to test Lua bindings with actual HW

	$ cmake .. -DUNIT_TESTING=on -DUNIT_TESTING_PORT_NAME1='/dev/ttyUSB0' -DLUA_BINDINGS=on ..
	$ make
	$ make test

	... snip ...

	4/5 Test #4: cram-lua-nohw-tests ..............   Passed    0.04 sec
	    Start 5: cram-lua-hw-tests
	5/5 Test #5: cram-lua-hw-tests ................   Passed    0.25 sec

	100% tests passed, 0 tests failed out of 5

Signed-off-by: Petr Štetiar <ynezz@true.cz>