config: build broker after modules
config: provide two environment vars for config

  FLUX_CONF_DIRECTORY
    sets a non-default path to keys and config
  FLUX_CONF_USEFILE=1
    forces the use of a config file (even if FLUX_TMPDIR is set)
config: flux-config using new conf environment vars
config: cmbd use new config environment vars
config: flux set FLUX_CONF_DIRECTORY unconditionally
config: require security directory to be set

You must call flux_sec_set_directory () after creating the security
context or subsequent calls will fail.
config: flux-keygen set keys directory

Require that FLUX_CONF_DIRECTORY be set.
Use it to make a call to flux_sec_set_directory ().
config: cmbd calls flux_sec_set_directory ()
security: remove HAVE_ZAUTH conditional

Let's not even pretend to support earlier flavors of ZeroMQ.
flux-snoop: drop support for earlier zmonitor vers
config: flux-snoop call flux_sec_set_directory ()
config: flux-config redefine confdir as a const
config: eliminate unnecessary cast in cmbd.c
config: ensure in-tree etc/flux has proper mode
config: fix flux.c typo in general.man_path usage
config: security.h should not define FLUX_DIRECTORY
config: fix flux usage message
config: update man pages