Declutter __init__ by using strategy selection

Instead of having there be a complicated __init__
function that has to make a bunch of complicated
decisions this change moves the logic for making
those decisions into a set of helper functions that
now select the various wait/stop/reject strategies
to use when retrying.

This will hopefully make it easier to add new
strategies as well as move forward to a path where
users can provide there own strategies (if they
so want to).