Add UPDATE_SYSTEM env var to run command

Base fedora docker images are appliance images that are not updated often. This UPDATE_SYSTEM=0 environment variable within the docker run command will execute a 'yum update' before freeipa-server installation or before restarting services. Currently used to update initial freeipa-server package from 4.0.0-1.fc21 to 4.1.1-1.fc22.