Docker CAS 6.6.x needs /etc/cas/thekeystore

We can create the /etc/cas/thekeystore immediately like this:

docker run -d --name cas -p 8443:8443 apereo/cas:6.6.4; docker exec -it cas keytool -genkeypair -alias cas -keyalg RSA -keypass changeit -storepass changeit -keystore /etc/cas/thekeystore -dname "CN=localhost"