Refactor MonClient, KeyRing

Refactor MonClient, KeyRing

MonClient should contain a KeyRing and a RotatingKeyRing. All the
MonClient users, except possibly csyn, don't want to manage those
objects themselves.

Don't chdir until after we have opened the KeyRing. If the KeyRing is at
a relative path, a chdir may make it inaccessible. Separate the chdir
function from the daemonize function.

Refactor the cmds argument parsing a little bit. Separate the special
actions from the normal operations of the daemon.

This should allow librados and libceph to support CephX finally! yay!

Signed-off-by: Colin McCabe <colin.mccabe@dreamhost.com>