Pin ARA to <1.0.0 and use stable setup interface to find callback plugin

ARA 1.0 will be released in the near future and isn't backwards
compatible. Pin it so it doesn't break things unexpectedly.

ARA ships simple setup modules to help figure out the paths
to where things are located.
These are backwards compatible from ARA 1.0 to 0.x.

Change-Id: I3fe3f4082279c2fd9a629605619a97aa5f5b0b73

tools/setup_gate.sh

@@ -89,17 +89,17 @@ function setup_ansible {
     RAW_INVENTORY=/etc/kolla/inventory
 
     # TODO(SamYaple): Move to virtualenv
-    sudo -H pip install -U "ansible>=2.4" "docker>=2.0.0" "python-openstackclient" "ara" "cmd2<0.9.0"
+    sudo -H pip install -U "ansible>=2.4" "docker>=2.0.0" "python-openstackclient" "ara<1.0.0" "cmd2<0.9.0"
     if [[ $ACTION == "zun" ]]; then
         sudo -H pip install -U "python-zunclient"
     fi
     detect_distro
 
     sudo mkdir /etc/ansible
-    ara_location=$(python -c "import os,ara; print(os.path.dirname(ara.__file__))")
+    ara_location=$(python -m ara.setup.callback_plugins)
     sudo tee /etc/ansible/ansible.cfg<<EOF
 [defaults]
-callback_plugins = ${ara_location}/plugins/callbacks
+callback_plugins = ${ara_location}
 host_key_checking = False
 EOF