Added listener to be able to set countdown value

With the listener one can set the countdown value using
$broadcast('countdown-set', value). This might be an edge case, but I
need to set a new countdown. This makes the countdown value dynamic set.
Issue #23 describes how to set the value on initialization but using
this one can change the value whenever necessary.
Last emitted millisecond is 0

Changed the order of execution to make 0 the last emitted millis value
for a countdown. Previously the last emit message was the value just
before 0. For example with a countdown with an interval of 1000 the last
emitted millis value was 1000.
Countdown set function and emit 0 as last value

With the listener one can set the countdown value using
$broadcast('countdown-set', value). This might be an edge case, but I
need to set a new countdown. Issue #23 describes how to set the value on
initialization but using this one can change the value whenever
necessary.

Also changed the order of execution of some code to make 0 the last
emitted millis value for a countdown. In the original code the last emit
message was the value just
before 0. For example with a countdown with an interval of 1000 the last
emitted millis value was 1000.
Revert "Last emitted millisecond is 0"

This reverts commit 7516570eebe752a4ece658d36190f5227a4d2cfa.
Revert "Added listener to be able to set countdown value"

This reverts commit 8651fd33e5799f1b43886e9e5a4df9874f0264ae.
Merge pull request #44 from johnparn/master

Added listener to be able to set countdown value