Use timer events instead. A side effect is that we now
support timeout in client mode. We also get much more
accurate timeouts. Previously starting a server with
a timeout of 4s, and GETing an endpoint that just looped,
would timeout somewhere between 3.5(!) and 8 seconds. Now
it times out between 4.0001 and 4.02s.
This will also make fixing pagelet timeouts much easier.
This is an incremental step towards moving it all the way
to hphp/server. This flattens base but doesn't untangle
the server files from lib_hphp_runtime
mwilliams