[patch] Allow keyword arguments in association proxy append()

[J Pellerin]

The attached patch allows association proxies to accept keyword arguments, which are passed to create(). When no creator function is specified, they are passed through to the __init__ of the created class. The assocation proxy example is also updated to include an example of passing in a keyword argument to set the price of an item.

[J Pellerin]

Add keyword argument support to association proxy

[Mike Bayer]

patched this in changeset:2091