Add indicators is_latest_version filter
Update indicator-job to allow for multiple is_latest_versions

Needed in order to properly filter the indicator versions
based on version and city_name for the indicator map and data
pages.

The django.conf.settings.OTI_CITY_NAME should be temporary,
and will be replaced by a user-defined default for the
app's uploaded city name.

Updated the indicator-version endpoint to return all current valid
city_name/version combinations, which included uploaded comparision
indicators.

Set is_latest_version = True only on successful indicator csv import
Update django translations, remove default city_name
Merge pull request #162 from WorldBank-Transport/feature/latest-version-filter

Add indicators is_latest_version filter