store login form in state tree

[brandly]

eventually fixes #18

we really only support the happy path. i think this is the plan:

• don't add to connections list until a connection has truly been established. keeping it elsewhere will allow better UI feedback
• maintain form state so you can click away from the tab and come back. just gotta clear it when a connection is established.
• handle on('errors'). it fires in situations like connecting to the server but your name is already taken
• render errors in form
• add back localStorage stuff. probably should go ahead and support a list of saved connections. wired up. needs some style.
• add a timeout. i tried connecting to 1.1.1.1 and it hung indefinitely.