Fix error handling in create

Signed-off-by: Raul Gutierrez S <rgs@itevenworks.net>
Py3k: {}.keys is dict_keys, not list

Signed-off-by: Raul Gutierrez S <rgs@itevenworks.net>
fix creating sequential znodes with no prefix (i.e.: /test/)

Signed-off-by: Raul Gutierrez S <rgs@itevenworks.net>