[nettime] Initial checkin of Network time plugin.

This commit was sourced from the following commit:

http://gitweb.merproject.org/gitweb?p=mer-core/ofono.git;a=commit;h=57f276b092ac398bdee0d2fbee48184f66130fb3
[nettime] Added test scripts.
[ril/rilmodem] Add real calls for revision and IMEI probe
releasing version 1.12phablet6
rilmodem/devinfo.c: using RIL_REQUEST_GET_IMEI for imei (works for both maguro and mako)
rilmodem/devinfo.c: only free revision/imei if it's valid
Re-merge from trunk.
[gril] Exit on RILD socket errors.
Adding a check target to debian/rules
rilmodem/devinfo.c: fixes from code review
[ril/rilmodem] Add real calls for revision and IMEI probe.

Approved by PS Jenkins bot, Tony Espy, Simon Busch.
Adding a test target to debian/rules.

Approved by Tony Espy, PS Jenkins bot.
Re-merge from trunk.
Fixed changelog merge error.
Re-merge from trunk.
[nettime] Fix NetworkTimeChanged signal in test/monitor-ofono.
Update debian/changelog to UNRELEASED.
[gril] Exit if errors occur during RILD socket intialization.

Approved by Ricardo Salveti, PS Jenkins bot.
Re-merge from trunk.
Added network time plugin which exposes RILD NITZ messages over DBus.

Approved by Ricardo Salveti, PS Jenkins bot.