Merge pull request #72 from SgtCoDFish/master

Fixes #70: PooledEntity: entity not fully reset
Entity uses long for id
PooledEntity correctly sets its id to 0 on reset
Changed getIndex() to getId()
Adds getEntities() to IntervalIteratingSystems and IteratingSystem for issue #71
Fixes GWT compatibility issue #73
Fixes comment in entity id
Renames id to uuid
Ups version to 1.3.0 pre-release
Ups version to 1.3.1 post release
Merge remote-tracking branch 'ashleyOrigin/master'