unsubscribe: Configure as csrf_exempt.
unsubscribe: Configure as csrf_exempt.

The reason we didn't have this before is that a GET to one of these
URLs would suffice to unsubscribe the user; but with the
List-Unsubscribe system, we need to allow POST from a third-party page
as well.

andersk/zulip,kou/zulip,hackerkid/zulip,andersk/zulip,hackerkid/zulip,zulip/zulip,kou/zulip,punchagan/zulip,eeshangarg/zulip,eeshangarg/zulip,andersk/zulip,hackerkid/zulip,zulip/zulip,eeshangarg/zulip,kou/zulip,zulip/zulip,punchagan/zulip,zulip/zulip,kou/zulip,eeshangarg/zulip,zulip/zulip,kou/zulip,punchagan/zulip,andersk/zulip,punchagan/zulip,punchagan/zulip,hackerkid/zulip,eeshangarg/zulip,punchagan/zulip,rht/zulip,hackerkid/zulip,rht/zulip,eeshangarg/zulip,rht/zulip,rht/zulip,andersk/zulip,andersk/zulip,zulip/zulip,kou/zulip,zulip/zulip,hackerkid/zulip,eeshangarg/zulip,andersk/zulip,rht/zulip,rht/zulip,rht/zulip,punchagan/zulip,hackerkid/zulip,kou/zulip