Description of problem:
Currently hawkular-wildfly-agent-installer requires the EAP to be stopped to install hawkular-wildfly-agent. It should be possible to install the agent while the EAP is running as well.

Version-Release number of selected component (if applicable):
mm DR04
eap7-middleware-manager-agent-0.29.3-1.Final_redhat_1.1.ep7.el7

How reproducible:
Always

Steps to Reproduce:
1. install EAP 7 (yum groupinstall jboss-eap7)
2. start it (systemctl start eap7-standalone)
3. install hawkular wildfly agent (yum install eap7-middleware-manager-agent-0.29.3-1.Final_redhat_1.1.ep7.el7.noarch.rpm)
4. configure the agent:
export JBOSS_HOME=/opt/rh/eap7/root/usr/share/wildfly/
java -jar ${JBOSS_HOME}/bin/hawkular-wildfly-agent-installer.^Cr --target-location=${JBOSS_HOME} --server-url=http://hawkular.bc.jonqe.lab.eng.bos.redhat.com:8080 --username=jdoe --password=password --config-only=true
5. update some configuration via jboss-cli and reload (e.g. /opt/rh/eap7/root/usr/share/wildfly/bin/jboss-cli.sh --connect --commands="/subsystem=datasources/data-source=ExampleDS:write-attribute(name=max-pool-size,value=12),reload")

Actual results:
After step 4 the standalone.xml is correctly update, but after step 5 all the changes are overwritten.

Expected results:
Changes should be permanent (done via jboss-cli)

Additional info:
Solutions would be to use jboss-cli and embedded server or admin-only mode which should be available for EAP 6 as well.