Add keystoneauth-core group
Add keystoneauth-core group

To enable a wider team (including those from the SDK effort) to have
a say in how keystoneauth is managed as a library, add a dedicated
core group for both the library and release. This will allow for
keystoneauth to include cross-team core members without needing
to add these members to the core team that manages keystone server
code.

The plan is to also include the keystone-core and keystone-release
groups respectively.

Change-Id: I40721df75e86e7dcd3b99ad5a4e78ddcfa432645

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