Upgrade underscore (from 1.6.0 to 1.7.0).
Merge branch 'master' of github.com:CIRB/django-fixmystreet

# By CIRB Jenkins (2) and David Franklin (1)
# Via CIRB Jenkins (1) and David Franklin (1)
* 'master' of github.com:CIRB/django-fixmystreet:
  Back to development: 3.0.15
  Preparing release 3.0.14
  fms 250: pro should have a button to request the reopening of a closed incident
Rename constants in uppercase.
Refactor templates using Underscore instead of home made.