Manual build trigger

Adding option to trigger build manually by specifying buildConfigID or buildID.
eg:
`openshift kube create builds --id="buildID"`
`openshift kube create builds --from-build-cfg="buildConfigID"`

When you want to re-run a build, I don't think you should look at the buildConfig. The buildConfig may have changed since the build was launched. It also doesn't contain information about the specific revision that the original build was run with. When I was thinking about this, I would think that you'd want to call createBuild with a copy of the original build resource parameters, not the generateBuild call.