re-ordered the list of artists returned by `legend_handler.HandlerErrorbar`

This is to address an issue raised on SO http://stackoverflow.com/questions/19470104/python-matplotlib-errobar-legend-picking.

As near as I can tell, `create_artists` is only ever called by `HandlerBase.__call__()` which then drops all but the first artist, which is returned by `__call__` and added to `legend.ledgendHandles`.  

Re-ordering the artist makes picking on them behave better (see the SO question at the top).

This technically breaks the API, but I would be surprised if anyone is actually using this (yes, http://xkcd.com/1172/).