[WFCORE-60] Runtime capabilities and requirements

Implements the aspects discussed under the "Runtime" section of https://community.jboss.org/docs/DOC-52712

This PR incorporates #107 which was foundational work.

The most important bit is https://github.com/bstansberry/wildfly-core/compare/cap-req?expand=1#diff-7 which illustrates the primary API management developers will use.

I have a couple other branches that illustrate the use of the API. I'm not submitting those commits as part of this because this is a lot for a reviewer to chew on. But have a look at the latter commits in these to see some of the relevant usage:

https://github.com/bstansberry/wildfly-core/tree/cap-req-4
https://github.com/bstansberry/wildfly/tree/iiop-jts
msg would better be off as StringBuilder