Combine call.Param list actions

[Jaymon]

Right now there are three different list actions:

• "store_list" - set to have a value like 1,2,3 be blown up to ['1', '2', '3']
• "append" - if multiple param values should be turned into an array (eg, foo=1&foo=2 would become foo=[1, 2])
• "append_list" - it's store_list + append, so foo=1&foo=2,3 would become foo=[1, 2, 3]

I'm sure I had a reason to have all these be separate at some point in the past but the reasoning has been completely lost to time and I think append_list should be the only way.

So basically, remove append_list and append and take the functionality of the current append_list and rename it store_list.

[Jaymon]

argparse action has append and extend, I think I can merge store_list and append_list into extend and keep action as is. I think that would mostly be consistent with how argparse does it.