Sets final announcement length to 10 seconds

Sets final announcement "Mission ends in 5, 4, 3, 2, 1. Mission
complete"
to 10 seconds instead of 12. This causes the time of the this
announcement to match
the time in the mission cards. Otherwise the time is off by 2 seconds.
Merge pull request #3 from tompen/correct_ending_time

Sets final announcement length to 10 seconds