Bug 1172036 - Vagrant: Run export_project_credentials during provision

This means there is one less manual step that has to be performed during
initial setup.

docs/installation.rst

@@ -63,12 +63,6 @@ Setting up Vagrant
 Setting up a local Treeherder instance
 --------------------------------------
 
-* Export oauth credentials for all data source projects
-
-  .. code-block:: bash
-
-     (venv)vagrant@local:~/treeherder$ ./manage.py export_project_credentials
-
 * And this line to your **host** machine's /etc/hosts so that you can point your browser to local.treeherder.mozilla.org to reach the VM
 
   .. code-block:: bash

puppet/manifests/classes/dev.pp

@@ -22,4 +22,11 @@ class dev{
     require => Exec["init_master_db"],
     user => "${APP_USER}",
   }
+
+  exec{"export_project_credentials":
+    cwd => "${PROJ_DIR}",
+    command => "bash -c 'source /etc/profile.d/treeherder.sh; ${VENV_DIR}/bin/python manage.py export_project_credentials'",
+    require => Exec["init_datasources"],
+    user => "${APP_USER}",
+  }
 }