Testing hacks on cooling

[ajf]

I've done a little hacking on the MOD-t to add a ducted part cooling fan and force the internal fan to be always on... It's not pretty at the moment but, after a couple of test prints, I'm seeing some improvement in print quality. 

More importantly, the issue with filament jamming in the hotend retaining nut has been eliminated.

I'm going to work on refining the part fan mount to make it prettier. And will also add some LEDs to light up the bed, 'cause LEDs are cool!