Very basic IRC Bot

Summary:
This is sort of a silly/fun project but I think there's some utility. For
example, mroch added some handlers to an eggdrop or something similar to look
for "D12345" and print out the title/link, which was actually pretty useful.

We could also add logging here and subsume the more-or-less unowned Facebook
tool that does the same thing, especially since we can get a bunch of good stuff
it doesn't support (like search) more or less for free.

This is also an easy way to provide some example code for writing Conduit system
agents.

This is a minimal implementation which creates a bot that connects to a
hard-coded server and sits there indefinitely. Next steps:

• Add conduit/sysagent support
• Write differential/maniphest/diffusion handlers
• Move configuration to the web interface (?) and integrate with phd
• Write a logging handler?

Test Plan:
Ran bot with "exec_daemon.php", it connected to the hard-coded server and sat
there indefinitely.

Reviewed By: aran
Reviewers: codeblock, mroch, tuomaspelkonen, aran, jungejason
CC: aran, epriestley
Differential Revision: 283