restructure unit_test_coverage.py to improve code coverage

[cjkrolak]

unit_test_coverage.py now imports utc which causes unit test coverage to be under-stated, restructure the file to avoid this issue.

[cjkrolak]

unit test coverage before changes to unit_test_coverage.py: Module	statements	missing	excluded	coverage
Total	1877	724	0	61%
email_notification.py	62	21	0	66%
honeywell.py	209	44	0	79%
kumocloud.py	173	32	0	82%
kumolocal.py	145	108	0	26%
mmm.py	218	162	0	26%
sht31.py	159	63	0	60%
sht31_flask_server.py	210	90	0	57%
supervise.py	69	18	0	74%
supervisor_flask_server.py	57	7	0	88%
thermostat_api.py	105	30	0	71%
thermostat_common.py	328	91	0	72%
utilities.py	142	58	0	59%

after code restructure, overall coverage improved by 10% and some missing modules were recovered: Module	statements	missing	excluded	coverage
Total	1971	574	0	71%
email_notification.py	62	9	0	85%
honeywell.py	209	44	0	79%
honeywell_config.py	4	0	0	100%
kumocloud.py	175	32	0	82%
kumocloud_config.py	4	0	0	100%
kumolocal.py	146	109	0	25%
kumolocal_config.py	7	0	0	100%
mmm.py	220	164	0	25%
mmm_config.py	7	0	0	100%
sht31.py	161	62	0	61%
sht31_config.py	37	3	0	92%
sht31_flask_server.py	210	90	0	57%
supervise.py	69	8	0	88%
supervisor_flask_server.py	65	10	0	85%
thermostat_api.py	105	0	0	100%
thermostat_common.py	348	38	0	89%
utilities.py	142	5	0	96%