start of soft matching feature branch
generic approach to categorical variables:
source interactions
simply source interactions
working towards generic categorical variable
implemented categorical variable
bug fix for interactions
sort
some clean up
some more tidying of initialize Data
break out data model initialization to separate file
handle interactions of source if sometimes source is missing
clean up 'Has Missing' checks
some more twiddling cleanup
Merge pull request #163 from open-city/soft_data_matching

Soft data matching
note that there is some third party code with different copywright closes #150
add coverall integration
coveralls
omit mekano code from coverage
move ordered dict out of core.py