limited ephemeral node support

each client gets a /eph symlink to /ctl/node/NODEID/client/IP-PORT
which is the ephemeral node for that client. this node automatically
gets deleted on client disconnect. thus, other clients can simply glob
over /ctl/node/*/client/* to find the current list of active clients.
additionally, the client can set the value of this ephemeral node by
calling SET('/eph', 'who am i', rev).

this feature is used to determine the list of running processes (which
would keep a persistent connection to doozer) on each node in the
cluster, and consequently have the process manager on those nodes
auto-start crashed processes.

known issue: the webui will freeze sometimes, but this is a known bug
even before this change which only seemed to have triggered it.
(cherry picked from commit a378599ae9453b72755e436a69982c215006c841)

Conflicts:
	peer/peer.go
	server/server.go
use empty value for the ephemeral node
(cherry picked from commit 0f16a8641264f34a046e5ce16c53622ba4334eef)
allow underscore in paths
(cherry picked from commit c70110d10aeef4f2891b85790f13f7e0fd7e28f1)
add -q (quiet) argument to suppress logging to console
http://bugs.activestate.com/show_bug.cgi?id=94744
(cherry picked from commit 5fea2ad72717c4d66ae078d28c0a8aa4c5e5be1a)
(cherry picked from commit 12392b14941ba84a5d999d4cfc86977778eeab44)
increase UDP packet size to accomodate potentially larger values
http://bugs.activestate.com/show_bug.cgi?id=97023
(cherry picked from commit a1eb8107d0cc019cd788a57bd5ff59421f6691df)