Updated to use Ruby 2.2 on rhel7.4 and added HPA

[georgegoh]

@chrisruffalo as discussed in our email, the first commit is for using Ruby 2.2, and the other is an enhancement to add HPA.

[chrisruffalo]

I can't remember all the details we talked about with this one. I'd like to refactor these changes into a common script that runs most of the same code for both CentOS and RHEL and delegates the parts that are different.

I'm worried that we are moving away from the ability to maintain a version/release agnostic build/workflow.

[chrisruffalo]

I've implemented your ruby 2.2 changes as part of #19 and it should work as part of any CentOS or RHEL version that uses software collections.

Forcing a specific minor version (like RHEL 7.4) may not be good to merge so we need to examine other avenues (like possibly enabling configuration on the input image stream in the build template).

I like the horizontal auto scaling but I think we may want to break that out into a separate template so that it can be applied separately if someone wants to do it that way.