Make polls easier and less clutter-y to set up

[flotwig]

Currently, setting up a poll requires a lot of messages in the channel where the poll is created. This is problematic because it sends users useless notifications and clutters up the channel history.

One solution would be to have poll creators interact with PantherBot via PM and then PantherBot could post only the finalized poll message to the channel.

[ghost]

Very much needed, and was planned, but DM'ing users and keeping channel contexts is very difficult the way we have it now. With our coming refactor this should be much easier

[arshbot]

Also, currently !poll does not allow for a question statement (or it is not easily shown how to make one)

And better documentation for how to use poll should be given