Health Check Fixes

This PR pulls in an updated `omnibus-software` which contains a number of health check fixes as outlined in: https://github.com/opscode/omnibus-software/pull/154. It also contains compatibility fixes for Omnibus 2.0+. 

Commit d950d3a will be updated to a final version once https://github.com/opscode/omnibus-software/pull/154 is merged.

/cc @opscode/release-engineers @opscode/engineering-leads