Add the ability for ola_recorder to record for a certain amount of time

[peternewman]

As raised in https://groups.google.com/forum/#!topic/open-lighting/IYniIKUXvI4

[peternewman]

@DragoonBoots did in and out points (and some other improvements) in #1648 . #1607 allows you to record for a certain duration so keeping this open until that's in too.