Merge pull request #1 from maxmind/master

Import geoip2.models
Merge remote-tracking branch 'upstream/master'

sync with remote to see if missing import has been fixed
remove extra dependency on geoip2.errors masking that geoip.data was not importing
all of its dependencies itself.
Added missing dependency to geoip2/database.py
Merge pull request #7 from kecaps/master

fixed import dependencies in geoip2.models