Rename get_publishpoint_url to get_publishpoint_streams

Make game_type and stream_type parameters optional.

Don't require clients to provide info we already know.
Simplify user-agent to only iPad

It's the only part of the string they seem to be sniffing for, so let's only send
that.

I noticed no decrease in bitrate streams with this. 2013 RedZone
archives were 4500. Latest game streams were 3000.
Small cleanup
Update readme

BaumSchorle's made a bunch of improvements. We should brag about them.
;-)