Switch install script over to Ansible devel branch

Switch over to Ansible devel branch due to the incompatible changes
between 1.9 and current development, as our ansible modules are
updated to support the newer code.

NOTE: This results in Bifrost being incompatible with Ansible 1.9.

env-setup.sh

@@ -16,8 +16,8 @@ if [ ! -d ansible ]; then
     git clone https://github.com/ansible/ansible.git --recursive
 else
     cd ansible
-    git checkout stable-1.9
-    #git pull --rebase
+    git checkout devel
+    git pull --rebase
     git submodule update --init --recursive
     git fetch