analytics: Add on_delete in foreign keys.
analytics: Add on_delete in foreign keys.

on_delete will be a required arg for ForeignKey in Django 2.0. Set it
to models.CASCADE on models and in existing migrations if you want to
maintain the current default behavior.
See https://docs.djangoproject.com/en/1.11/ref/models/fields/#django.db.models.ForeignKey.on_delete

verma-varsha/zulip,timabbott/zulip,punchagan/zulip,rht/zulip,zulip/zulip,eeshangarg/zulip,jackrzhang/zulip,vabs22/zulip,jrowan/zulip,jrowan/zulip,jrowan/zulip,timabbott/zulip,amanharitsh123/zulip,dhcrzf/zulip,brainwane/zulip,synicalsyntax/zulip,mahim97/zulip,zulip/zulip,punchagan/zulip,rishig/zulip,punchagan/zulip,jrowan/zulip,amanharitsh123/zulip,Galexrt/zulip,andersk/zulip,timabbott/zulip,showell/zulip,rishig/zulip,shubhamdhama/zulip,dhcrzf/zulip,rht/zulip,zulip/zulip,shubhamdhama/zulip,Galexrt/zulip,tommyip/zulip,kou/zulip,verma-varsha/zulip,Galexrt/zulip,brockwhittaker/zulip,showell/zulip,timabbott/zulip,Galexrt/zulip,verma-varsha/zulip,timabbott/zulip,synicalsyntax/zulip,brainwane/zulip,brockwhittaker/zulip,jackrzhang/zulip,kou/zulip,jrowan/zulip,hackerkid/zulip,vabs22/zulip,zulip/zulip,rht/zulip,vaidap/zulip,brockwhittaker/zulip,shubhamdhama/zulip,timabbott/zulip,shubhamdhama/zulip,vabs22/zulip,shubhamdhama/zulip,tommyip/zulip,rht/zulip,mahim97/zulip,amanharitsh123/zulip,showell/zulip,punchagan/zulip,mahim97/zulip,timabbott/zulip,punchagan/zulip,verma-varsha/zulip,dhcrzf/zulip,showell/zulip,brainwane/zulip,hackerkid/zulip,tommyip/zulip,brockwhittaker/zulip,dhcrzf/zulip,rishig/zulip,hackerkid/zulip,eeshangarg/zulip,mahim97/zulip,rishig/zulip,andersk/zulip,eeshangarg/zulip,andersk/zulip,eeshangarg/zulip,hackerkid/zulip,zulip/zulip,zulip/zulip,dhcrzf/zulip,verma-varsha/zulip,Galexrt/zulip,amanharitsh123/zulip,vabs22/zulip,andersk/zulip,jackrzhang/zulip,jackrzhang/zulip,hackerkid/zulip,vabs22/zulip,tommyip/zulip,andersk/zulip,jackrzhang/zulip,zulip/zulip,kou/zulip,vaidap/zulip,jackrzhang/zulip,mahim97/zulip,kou/zulip,brainwane/zulip,rht/zulip,andersk/zulip,hackerkid/zulip,jrowan/zulip,shubhamdhama/zulip,vaidap/zulip,kou/zulip,mahim97/zulip,synicalsyntax/zulip,vaidap/zulip,kou/zulip,showell/zulip,Galexrt/zulip,hackerkid/zulip,amanharitsh123/zulip,brockwhittaker/zulip,brainwane/zulip,synicalsyntax/zulip,jackrzhang/zulip,tommyip/zulip,synicalsyntax/zulip,synicalsyntax/zulip,verma-varsha/zulip,rht/zulip,brainwane/zulip,vabs22/zulip,eeshangarg/zulip,kou/zulip,shubhamdhama/zulip,andersk/zulip,dhcrzf/zulip,showell/zulip,tommyip/zulip,vaidap/zulip,eeshangarg/zulip,rishig/zulip,dhcrzf/zulip,rishig/zulip,Galexrt/zulip,rishig/zulip,vaidap/zulip,brockwhittaker/zulip,showell/zulip,tommyip/zulip,synicalsyntax/zulip,rht/zulip,brainwane/zulip,punchagan/zulip,amanharitsh123/zulip,punchagan/zulip,eeshangarg/zulip