Add change_password option for openstack providers

Document as well

doc/topics/cloud/openstack.rst

@@ -90,3 +90,12 @@ Here is an example of a profile:
 
 ``image`` can be one of the options listed in the output of ``nova image-list``.
 
+
+change_password
+~~~~~~~~~~~~~~~
+If no ssh_key_file is provided, and the server already exists, change_password
+will use the api to change the root password of the server so that it can be
+bootstrapped.
+
+.. code-block:: yaml
+    change_password: True

salt/cloud/clouds/nova.py

@@ -553,6 +553,7 @@ def create(vm_):
                     __opts__
                 )
             )
+        if vm_['key_filename'] is None and 'change_password' in __opts__ and __opts__['change_password'] is True:
             vm_['password'] = sup.secure_password()
             conn.root_password(vm_['instance_id'], vm_['password'])
     else:

salt/utils/cloud.py

@@ -291,6 +291,15 @@ def bootstrap(vm_, opts):
             'system for the password.'
         )
 
+    if key_filename is None and ('password' not in vm_ or not vm_['password']):
+        raise SaltCloudSystemExit(
+            'Cannot deploy salt in a VM if the \'ssh_keyfile\' setting '
+            'is not set and there is no password set for the vm. '
+            'Check your provider for the \'change_password\' option.'
+        )
+
+
+
     ret = {}
 
     deploy_script_code = os_script(