[whispersystems] Developer experience improvement

[Alex Newman]

I am trying to jump into working on the server. I filed a bunch of pull
requests as noob pull requests to get started. I intend on first making it
a comfy home for noobs to whisper like me.

https://github.com/WhisperSystems/Signal-Server/pull/79

I noticed some additional things I'd be happy to cleanup if I get the rights

- Cleanup old git branches. We have a bunch of them just rotting

- Cleanup the old pull requests. In general I think it's better to just
close out stale pull requests
https://github.com/WhisperSystems/Signal-Server/pull/17 or #22 and even
#75 #77. Just say thankyou thanks but no cigar. It's way better than just
leaving them open forever. We can always re open the pull request if they
update the branch, but honestly it's better if you close requests open for
more than a year and just reference the old ones.

- There's no way to add new issues. I removed the stale documentation line
from the README but we should have a place for issues and a plan on what to
improve. Happy to help out here.

- A community call to action. Do we want everyone to talk on the mailling
list? Perhaps we could support sometime realtime? I am sure this must have
already been discussed. Happy to idle on irc.

- A lot of these pull requests could have some guidance on how to do things
cleaner. Maybe we should cook up a contributors guide?

-Alex