[SPIKE] How to configure multiple OSX slaves

Current OpenShift template is able to run multiple parallel slaves for running Android builds thanks to Jenkins Kubernetes plugin.

However it only allows 1 OSX slave.

We need to think about how to configure multiple slaves with ease.

Although configuring a slave is super easy (just put a config.xml file under $JENKINS_HOME/nodes/<slave-name>/), these are problematic:

• We reference the node name (slave name) in Jenkinsfile. But ideally, Jenkins should pick any OSX slave which is not busy. Perhaps: https://wiki.jenkins-ci.org/display/JENKINS/Compound+Slaves

• We need to make the template somehow accept N number of slave configuration parameters.

What we want out of this JIRA is to review the work already done and create any JIRAs required to get this piece of work done.
There had been some work done previously so lets leverage this towards the estimating how much work will be required.