Added checks enforcements rule to the developers manual
Added checks enforcements rule to the developers manual

This change adds the convention we established for checks
during the weekly meeting on 01-09-2014 to the developers docs.

Change-Id: I2b202ac018435b7c671490f9f036e700685e85f3

openstack/zaqar,openstack/zaqar,openstack/zaqar,openstack/zaqar