TM1 outputs should have numeric county identifier

[akselx]

Currently, in the county_marginals table, the county variable is the string representation of counties, and housed on the index.

The population synthesizer expects the numerical integer county designation named COUNTY (1 through 9, starting with San Francisco, moving around the bay counter-clockwise) - mapping is here. The old format had a county_name variable that was a string representation.

Numerical value is already present on taz_geography so it should be trivial to add.