fix OpenStack_2_NodeDriver docstring
fix OpenStack_2_NodeDriver docstring

> This actually inherits get_image from
> OpenStack_1_1_NodeDriver. - pquentin

Signed-off-by: Quentin Pradet <d17611fde61d73f8de1b8b01bc47d446558ccd8e@apache.org>

apache/libcloud,ByteInternet/libcloud,mistio/libcloud,Kami/libcloud,Scalr/libcloud,mistio/libcloud,andrewsomething/libcloud,andrewsomething/libcloud,Kami/libcloud,Kami/libcloud,vongazman/libcloud,StackPointCloud/libcloud,ByteInternet/libcloud,vongazman/libcloud,ByteInternet/libcloud,vongazman/libcloud,apache/libcloud,andrewsomething/libcloud,Scalr/libcloud,apache/libcloud,Scalr/libcloud,mistio/libcloud,StackPointCloud/libcloud,StackPointCloud/libcloud