AP_Scripting: added UltraMotion servo driver #4331

Job	Run time
build-gcc-heli	6m 46s
build (base)	6m 41s
build (clang)	8m 46s
autotest-heli (sitltest-heli)	14m 11s
autotest (sitltest-copter-tests1a)	12m 6s
autotest (sitltest-copter-tests1b)	13m 37s
autotest (sitltest-copter-tests1c)	16m 12s
autotest (sitltest-copter-tests1d)	13m 34s
autotest (sitltest-copter-tests1e)	13m 42s
autotest (sitltest-copter-tests2a)	13m 36s
autotest (sitltest-copter-tests2b)	33m 4s
	2h 32m 15s

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