Require openstack-doc-tools 0.8.2

This is the current release and it is needed to fix building with
current infrastructure.

Change-Id: I4e7fa0da6429feb87f61b527c4a6ca5d617b1255
Add croniter dependency

A cron library, will be used in Ceilometer alarms.

License is MIT, lower bound is based on the added Py3 support.

Is also used by Mistral: https://github.com/stackforge/mistral/blob/master/requirements.txt

Change-Id: I9b818c171d9ca2e4e8afd8058769be471b2ff800
Blueprint: time-constrained-alarms
Merge "Add croniter dependency"
Merge "Require openstack-doc-tools 0.8.2"
migrate 0.8.4 is bad, block it

migrate 0.8.4 does a non conditional require on ibm db2 code. This
isn't correct, and that version needs to be blocked.

Change-Id: I087dc93543843a1f8d5556f3e21a73b1673ae54a