Remove unused code

[bendnorman]

I removed everything in #250 except for the co2_estimates table because the counties data mart table depends on code in the co2_dashboard module. I could delete the co2_estimates module by moving the private functions counties uses to the helpers module or the counties module

[TrentonBush]

I made one small change to src/dbcp/data_mart/__init__.py to stop it from creating the defunct co2_dashboard table