Prior to this change, create_node() would double-encode certain url
params: once when quote()'ing in _get_encoded_params(), and again in
urlencode().
This would cause HTTP 400 errors when creating a node with a name that
contains a url-encodable character, like "my+test+node".
Reviewed-by: Alfredo Deza <adeza@redhat.com>
Change-Id: I237e2988e168af81e623d3f065753f2e9b617696