Remove equip maint migration (not ready), temp now decimal

Removed the equipment maintenance migration as the procedure isn't
quite ready for use yet. Added a decimal point to the temperature
fields of WaterTestLogs
Added target params to aquariums

Added target temperature, KH, and pH to aquarium. This is for a future
feature which helps highlight when water tests are too far off of
the desired norms.

Hmm, in hindsight, it may be better to simply add in ranges instead of
exact targets...hmm...