v0.12.0 release

• Authentication is now optional as not all Jenkins instances have
  authentication enabled by default. Credit: @dougforpres
• Ability to retrieve build details so that more than just (lamp color) is
  available. Credit: @dougforpres
• Ability to retrieve build test-results for those builds that have them.
  Credit: @dougforpres
• Option to follow any 301/302 responses. This allows POST to build to follow
  the redirect and end up with a 200 response. Credit: @dougforpres
• Minor change to the POST requests handling where jenkins instances with a
  proxy returns 411 if no form data is specified. Fixed by sending an empty
  hash. Credit: @dougforpres
• As of Jenkins release 1.519, the job build returns a 201 code instead of 302.
  This was resulting in an exception and the exception handling is modified to
  handle this condition.
• The jobs that are not built yet have a new color (notbuilt) in the recent
  version of jenkins (> 1.517) which resulted in invalid status. This is fixed.