FIX jaws.collide with arrays of circles

[belen-albeza]

jaws.collide doesn't work when colliding a circle vs a list of circles or a list of circles vs another list of circles. This patch fixes:

• Circles vs Circles collisions in jaws.collide
• Two tests in collision detection that were commented that tested these circles vs circles case.
• A test in collision detection with callbacks that was expecting a non-collision between two colliding circles (?)

PS: I haven't run build.rb, so if this pull request gets through, it will need to be re-run.

[ippa]

Thanks! =) new build up.

[belen-albeza]

Thanks to you for the awesome lib :) :+1: