Added an option to start the game slowly.

Used for slower servers, with the command /uh start slow.
The teams are teleported with a delay, into the air (level ~200) and the game is really started using the command /uh start slow go .
Fixed a bug about the health objective being null before the first damage.

Also, updated the Player.setHealth() calls to use double numbers, because the use of integers is deprecated.
Typo fail :D
Improved /uh team list
The state of the player (dead or alive) is now shown in the list, if the game is running.
Maven is back! [First: structure]
Maven is back! [Second: pom pom pom]