Remove tools/validate.py
Remove tools/validate.py

The gates are using tools/test.py now and thus we can
delete tools/validate.py.

Change-Id: I38969ac13b78ec7429b73c32bfc9a159fabcd556

openstack/openstack-doc-tools,savinash47/openstack-doc-tools,savinash47/openstack-doc-tools,openstack/openstack-doc-tools,savinash47/openstack-doc-tools