Added characteristics of SF_Public_Buildings.
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Added characteristic of SF_Transit/{agency,routes,stops}
Merge remote-tracking branch 'upstream/master'
Merge pull request #7 from alejandrofcarrera/master

Added data characteristics for SF_311_3Months, SF_GIS, SF_Transit/{calendar,calendar_dates,shapes}.
Merge pull request #8 from baraalex/master

Added data characteristics for SF_Private_School, SF_Public_School, SF_Transit/{fare_rules,stop_times}.