Add prepare_orca_dependendencies to pull orca and gpos releases from github

concourse/prepare_orca_dependencies.bash

+#!/bin/bash
+
+set -u -e -x
+
+setup_gpos() {
+    gposdir=$1
+    wget -P $gposdir https://github.com/greenplum-db/gpos/releases/download/v1.138/bin_gpos_centos5_release.tar.gz
+}
+setup_gporca() {
+    gporcadir=$1
+    wget -P $gporcadir https://github.com/greenplum-db/gporca/releases/download/v1.640/bin_orca_centos5_release.tar.gz
+}
+
+main() {
+    yum -y install wget 
+
+    setup_gpos bin_gpos
+    setup_gporca bin_orca
+}
+
+main "$@"

concourse/prepare_orca_dependencies.yml

+platform: linux
+image: docker:///pivotaldata/gpdb-devel-gcc5#centos6
+inputs:
+  - name: gpdb_src
+outputs:
+  - name: bin_gpos
+  - name: bin_orca
+run:
+  path: gpdb_src/concourse/prepare_orca_dependencies.bash