Make devel build of mce log important external triggers by default

Events logged are:
* Time spent in suspend (via evdev inputs and mono vs boot time diff)
* Proximity sensor state (from evdev orsensorfw / synthesized within mce)
* Alarm state (D-Bus signal from alarm ui)
* Call state (D-Bus signals from ofono)
* CPU keepalive service (D-Bus method calls from clients)
* Display blanking pause service (D-Bus method calls from clients)
* Display blank/unblank alert leds (sysfs and D-Bus ipc with lipstick)
* Display on/dim/off requests (D-Bus method calls from clients)
* Display state changes (mce internal)
* Device lock status (D-Bus signals from lipstick)
* Tklock status changes (mce internal)
* Tklock state requests (D-Bus method calls from clients)

[mce] Make devel build of mce log important external triggers by default
Use CLOCK_BOOTTIME as clock source when logging to stderr

Previously CLOCK_MONOTONIC was used, but monotonic time does not advance
when the device is suspended and thus is not ideal for debugging issues
involving suspend.
Merge pull request #129 from spiiroin/devel_logging

Make devel build of mce log important external triggers by default