Allow disabling of automatic screen blanking from lock screen

New config setting "/system/osso/dsm/locks/tklock_blank_disable".

When enabled, tklock module uses longer timeouts for display
dimming / blanking. Effectively the lock screen is shown until
power key is pressed.

The config setting can be toggled with:
  mcetool --set-tklock-noblank=enabled|disabled
Setting tklock_blank_disable blocks automatic display dim/blank forever

The fake dim/blank timeouts now - in addition to using longer than normal
delays - repeat without performing the dim/blank action.
System startup ready detection is based on init-done flag file

Support functionality in filewatcher module hides the details of
processing inotify events from glib io watch.

Display plugin uses filewatcher to unblock late suspend when
/run/systemd/boot-status/init-done flag file is created.

If /run/systemd/boot-status directory does not exist when mce is
started up, mce waits uptime to reach 60 seconds before unblocking
late suspend.

In any case late suspend is blocked for 10 after mce startup.
Merge pull request #34 from spiiroin/do_not_blank_lockscreen

Allow disabling of automatic screen blanking from lock screen
Merge pull request #35 from spiiroin/startup_watch

System startup ready detection is based on init-done flag file