Add test cases for Clock

Add test_clock_add_alarm_multiple_times
Add clock test cases

test_clock_set_alarm_repeat;
test_clock_set_alarm_snooze;
test_clock_set_alarm_sound;
Address pep issues for #432

Address pep issues for #432.
test_clock_add_alarm_multiple_times.py
test_clock_set_alarm_repeat.py
test_clock_set_alarm_snooze.py
test_clock_set_alarm_sound.py
Re-implement tap on value selectors for #432

Address issues for #432.
test_clock_add_alarm_multiple_times.py
test_clock_set_alarm_repeat.py
test_clock_set_alarm_snooze.py
test_clock_set_alarm_sound.py
Move local parameters to class for #432 and add test case for #440

Move local parameters to class for #432 and add test case for #440
test_clock_set_alarm_repeat.py
test_clock_set_alarm_snooze.py
test_clock_set_alarm_sound.py
test_clock_set_alarm_time.py
Remove Tab for #432

only test_clock_set_alarm_sound.py is modified
Added test_settings_passcode.py for #477
Disable passcode in cleanUp(). #477
Eliminated the domain from URL. #503
Test notification bar for #459
Note: double_tap() doesn't work.
Eliminated the domain from URL. #503
Modified the _passcode_enable_locator.
Merge remote-tracking branch 'mozilla/master' into issue_459
Unxfail some tests that are consistently passing
Use script to open notification bar.
Update and re-enable the test_settings_cell_data
Remove logic in test_settings_cell_data due to more robust test setUp
Modified manifest.
Merge remote-tracking branch 'upstream/master' into fix_settings_cell_data
Upaded fail message, removed unused code.