[ofiwg] Travis CI testing of libfabric and fabtests

[Hefty, Sean]

> There are several github projects available that provide continuous
> integration testing.  Unless there is an objection, I plan on setting up
> Travis CI to test both libfabric and fabtests.  The current intent is just
> to see what we can do with it.  For example, verify the build, test that
> pull requests work with fabtests, look for regressions, etc.

With the help of several individuals (and, my personal favorite, trial and error development), Travis CI is now performing basic tests on both the libfabric and fabtests github trees.  Both repositories check that all pull requests build and the sockets provider can run all fabtests.  Work to expand the testing (such as building all providers) is ongoing.

I've also enabled branch protection to the upstream trees.  Now that Travis CI is working, I'd like to propose that we require status checks to pass before pull requests can be merged.  The only drawback that I see to this is that there will be a small delay (~5-10 minutes) before simple pull requests can be merged.

- Sean