Translate transit_indicators choices classes in django

These translations are done in Django for the following reasons:
  - Reduce coupling between the angular/django apps
  - Reduce amount of copy/pasting and repeated string definitions
    in the angular app.

Other options explored for translating these choices strings included:
  - Sending an angular-translate key as the django human-readable text
    and translating client side
  - Wrapping django/angular translations in a management/grunt command
    that would combine to a single po file to be sent to translators
Add example nvd3 angular charts
Merge pull request #126 from WorldBank-Transport/feature/i18n-django-choices

Translate transit_indicators choices classes in django
Merge pull request #127 from WorldBank-Transport/feature/nvd3-directives

Add example nvd3 angular charts
Fix issues with indicators CSV import.

Add missing field to field names list.
Autonumber ID field (do not use value imported from CSV).
Create new IndicatorJob so imported indicators have a version.
Merge pull request #128 from flibbertigibbet/feature/endpoint-for-d3

Fix issues with indicators CSV import.