Add support for claiming in-game usernames

[vmunich]

Usage:

After session = poko_session.authenticate():

session.claimCodename('desired_username')
codename: "desired_username"
user_message: "Codename is claimed."
is_assignable: true
status: SUCCESS

[rubenvereecken]

What do you say we switch to calling it Username instead? I'll probably send in a whooole bunch of renames to the protobuf repository anyway. A lot of the message names honestly suck.

Otherwise this is looking great!

[vmunich]

That's fine :) I called it like the other methods were called. One thing I realized is, you can change your username whenever you want with this call, even set your username to a username that's already being used. The status returns ALREADY_IN_USE but it changes the username anyway :D

[vmunich]

Removed the conflicting code.

[dnsBlah]

@vmunich Unfortunally it's solved now, if there already is a codename set, you can't change it anymore. You can only change 1 time now :(

[vmunich]

@dnsBlah yea that's sadly true :(

[dmadisetti]

So this is no longer valid?