Shave 10 seconds off UT run time.

No need to wait for any time at all when polling - it's the
instant events we're interested in.

Real run time goes from 51.8s to 41.4s on my box.
Ability to log timestamps. Occasionaly useful.
Allow control of LVC poll timer.

Leave it at 1000ms in production for efficiency.

Set to 10ms in UT for speed.

This saves 6s real time (of 41s), at a cost of 0.2s user time, on
my machine.
Merge pull request #35 from Metaswitch/ut-speedup-1

[Reviewer: Andy] UT speedup part 1