Add best and worst status details for conditional-step plugin.

In order for the conditional step plugin to work properly, a more
detailed status is required otherwise the current build status is not
evaluated properly and is set to SUCCESS in all cases.
A local mapping of the java hudson.model.Result class was created to
unify build statuses names, ordinal and color scheme.

Change-Id: If8a0090b7cd51551ef6756361f6e45af3df1218d
Merge "Add best and worst status details for conditional-step plugin."