Create Project on GitHub via Otto

[jwright]

As a user
I should be able to create a project on GitHub with commands via Otto
So that I can easily create GitHub projects from Slack

[jwright]

Successful conversation flow:

@ user > create project
@ otto > under what GitHub account do you want to create the project under?
@ otto > -- display a dropdown of accounts --
@ user > -- selects account --
@ otto > what is the name of the project?
@ user > <name of project>
@ otto > The project <name of project> was created on GitHub at <url>.
@ otto > The git url is <ssh url>