Adds cm_RankUpServers() and cm_RankServer()

Adds cm_RankUpServers() and cm_RankServer()

This adds the functions cm_RankUpServers() and cm_RankServer() to
the Windows cache manager. cm_RankUpServers() steps through the
list of servers, and calls cm_RankServer(), which in turn re-ranks
the servers that are currently up based on rx peer statistics as
exposed by rx_GetLocalPeers().

cm_RankUpServers() is called every 10 minutes by the cache manager
daemon, so as to allow re-ranking of the servers.

Also added is the struct server->adminRank data structure, to
allow for the modification of the rank that the admin has set,
without but basing this modification on the admin-set rank.

Change-Id: I118b885e179e4f84901dd9a3180ce821f194feb8
Reviewed-on: http://gerrit.openafs.org/317
Tested-by: Jeffrey Altman <jaltman@openafs.org>
Reviewed-by: Derrick Brashear <shadow@dementia.org>
Reviewed-by: Jeffrey Altman <jaltman@openafs.org>