Bump the version number for 11.8.2 release candidate.

Bump the version number to 11.8.0 for release.

Bump the version number for RC.

4th RC for 11.8.0.

Bump the version number to 11.8.0.rc.3 for a new RC build.

Bump the version number for RC 11.8.0.

Release Candidate 1 for Chef 11.8.0.

Development version for Chef 11.10.0.

Release Candidate 0 for Chef 11.8.0

use pessimistic version constraint

- this is compatible with gem versions from 11.6.0 with minimal
  changes.
- mixlib-shellout differs in windows-versus-unix due to version pinning
  in windows-pr picking up old mixlib-shellout on windows, this is
  not fixed, and left similar to 11.6.0
- gem versions should be levelled up for 11.8.x and beyond
- newly built 11.6.0 will pick up new mixlib-config 2.0 which is
  a delta from the downloadable omnibus builds, 11.6.2 will not
  pick up mixlib-config 2.0