FishLight_PCB: Add water level sensors

The water level sensors will be used to sense when a water top off is
needed and to ensure that the water reservoirs do not get too low and
potentially burn out my pumps.  Also removed a temp sensor because I
don't think 3 external temp sensors are really necessary.

Water level sensors are from Adafruit: http://www.adafruit.com/products/464
FishLight_PCB: Routed power lines and sized them right

Moved a few things around and then routed the power lines for the
12V and 24V lines.  Also sized them appropriately for their max
current of about 7A and 15A respectively.
FishLight_PCB: Place bypass caps and move stuff

Placed the bypass caps for each device and then moved some things around
to make more room as needed.  Also correctly linked the Sparkfun and
Adafruit libraries so that I could change footprints and stuff.
FishLight_PCB: Ran DRC and fix some errors

Fixed some errors after running a DRC pass.  Many errors were
complaining about stupid things like wires overlapping with pads or vias
to ground from a pad so these were mostly approved.  Moved some things
around to fix the issues that were legitimate.
FishLight_PCB: Lots of changes

Updated the package for the AD5248 digital potentiometers so that the
pins do not cause DRC errors.  Also continued routing and moved around
the LED ground connections so that they would be easier to use.  Also
changed the address assignments for the INA219 current sensors so that
they would be easier to route.  Did a DRC check and approved a number of
overlaps.  I also made a few attempts at putting in flyback diodes but
they are too big for my small design.  I may need to revisit this.  Also
looked into fuses for the AC devices but I did not find any designs at
Sparkfun that used fuses on their SSRs so I can probably skip this for
now.  Again, may need to revisit this.