when improved_sanitation.none is True, then num_toilets_total should be 0 instead of NA,

with tests for it in T1_TestLGAData.R
Merge branch 'master' of https://github.com/SEL-Columbia/nmis into improved_sanitation
Merge pull request #206 from SEL-Columbia/improved_sanitation

when improved_sanitation.none is True, then num_toilets_total should be ...