[ofiwg] libfabric v1.5.0rc1 now available

[Hefty, Sean]

Release candidate 1 for v1.5.0 is available at:

https://github.com/ofiwg/libfabric/releases/tag/v1.5.0rc1

Developers, please validate this version and report any issues.  There is one outstanding pull request against one of the providers, so I'd like to target rc2 for around 7/19.

I have not created a release candidate for fabtests, as there are open pull requests that add testing for a significant number of features.  I'd like to include that testing as part of the 1.5 release, but we need to verify that the tests themselves are at least mostly bug free. :)

- Sean