Update README.md
Update README.md
rename record distances to more accurate field distances
allow comparators
moved custom comparator example to csv_example
only 'Custom' field types are allowed to have custom comparator, better error messages if can't load picked data, updated csv_example and mysql_example'
Merge pull request #86 from open-city/custom_comparator_branch

Custom comparator branch
typo in documentation of csv_example
some small fixes in the docs of csv example
clean up of convenience function and csv_example
fixed many, but not all errors in true_ids.csv
allow for missing data, closes #39
fixed broken test
Update README.md
Update README.md
renamed 'Missing' field parameter to 'Has Missing'
Merge pull request #87 from open-city/missing_data

Missing data
fixes #93
Rewrite of haversine/jaccard routines to take native data types rather than strings; corresponding changes to setup and init files
Merged upstream changes from the master