ashley-1.5.0

• API addition: adds getFamily() method to IntervalIteratingSystem and IteratingSystem. Commit 55241f5.
• API change: IntervalSystem's update() method is now final, as it doesn't make sense to override it. Commit bffa44c.
• Update: updated Libgdx version to 1.6.0. Commit 9b0eb90.
• Enhancement: allows IntervalSystem to update faster than the main loop. Issue #151.
• Enhancement: improved hashCode() and equals() implementation of Family. Commit b01cb15.
• Bug fix: fixed GWT build and made a Jenkins job to make sure we also test GWT integrity. Commit e2be43e.
• Bug fix: empty Family now matches empty entities. Commit db1286f.