fix(app): adds LOGIN_URL to settings.base
feat(models): adds is_suppressed field to Incident model

part of  #46
fix(app): adds django-braces==1.4.0 and updates versions for gevent==1.0.1 and gunicorn==18.0
test(factories): adds User and Suppressor factories

part of #46
test(rules_engine): tests suppression pipeline

part of #46
feat(rules_engine): adds support for suppression of incidents

fixes #46