config: return EINVAL on put/get keys with embedded slashes
config: update t0001 to avoid use of / in keys
config: flux should work without a config file
config: flux-config should work without a config file
config: cmbd should work without a config file
config: generate in-tree keys as last build step
config: add flux --secdir and set FLUX_SEC_DIRECTORY
config: flux-snoop use FLUX_SEC_DIRECTORY
config: flux-keygen use FLUX_SEC_DIRECTORY
config: broker use FLUX_SEC_DIRECTORY
config: t/t0001 use flux --secdir
config: update flux(1) man page