[Wishlist] Add kwargs support to APIObject.modify_and_apply

[jdandrea]

Presently it appears as though I need to branch to two different calls to APIObject.modify_and_apply() because I can't pass in kwargs to modifier_func the way I can with Selector.until_all() and success_func.

Might it be possible to add support for that? If it is, and I have a chance to, I may try adding it myself via a fork/PR. But I wanted to check first. Thanks!