Add requirements gate for solum project
Add requirements gate for solum project

Both solum and python-solumclient projects are in
requirements/projects.txt, so add requirements check for them.

Change-Id: I318c3ea4af8deedb9eeee63d6b07f64d4f489de8

osrg/project-config,anbangr/osci-project-config,osrg/project-config,coolsvap/project-config,Tesora/tesora-project-config,openstack-infra/project-config,dongwenjuan/project-config,noorul/os-project-config,noorul/os-project-config,anbangr/osci-project-config,Tesora/tesora-project-config,dongwenjuan/project-config,openstack-infra/project-config,citrix-openstack/project-config,open-switch/infra_project-config,open-switch/infra_project-config,citrix-openstack/project-config,coolsvap/project-config