Fixes Ambari repo used by HDP 2 image generation script

This patch fixes a problem in the HDP "hadoop-hdp"
  image generation element.
Some recent changes to the Ambari online yum
  repositories have caused a breakage in the HDP
  image-generation process.
This patch resolves this problem by modifying
  the HDP 2 image generation process to use the
  same repo URL used by the HDP 1 generation process.
  Currently, both versions of HDP use Ambari 1.4.3.38, so
  using the same repo URL is a valid choice.
This patch has been submitted to resolve the
  current build breakage for HDP images.

Closes-Bug: #1349893

Change-Id: I9ae0cb98b5085225fccfa2cb05a19a01c8d8ed8d
Merge "Fixes Ambari repo used by HDP 2 image generation script"