Merge pull request #21 from garlick/flux-config4

misc out of tree/side install fixes
doc: flux -h should list flux-config subcommand
doc: update flux(1) after rework
doc: correct flux-config usage output
doc: add flux-config(1)
doc: spellcheck man pages
doc: add internal help to flux cmd driver

flux help CMD displays manpage for flux-CMD.
Set MANPATH to [config man_path]:install-dir
so this works even when side-installed to a place not in the
system man search path, or in-tree (if configured).
doc: configure in-tree help

Set man_path in in-tree flux.conf to point to $abs_top_builddir/doc.

During the build in doc, ln -s cmd man1 to make man(1) happy.
(We could have git renamed cmd to man1, perhaps a more reasonable
naming convention, but I didn't think it was worth churning history)
doc: update flux(1) and flux.c for "flux help"
Merge pull request #23 from garlick/doc-updates

misc doc updates, add "flux help cmd"
live: generate "live.ready" after all say hello
cmbd: start shell only after live.ready event

The idea is to wait until comms is wired up before spawning shell
and any test code that depends on a stable session.

In addition fixed a bug:
The api module began hitting this assert:
   zloop.c:303: zloop_set_tolerant:
     Assertion `item->socket || item->fd' failed.

rank0_shell() closes STDIN_FILENO, and the api module gets it back
from accept(), then passes it to zloop (via the module machinery).
zmq_poll has a big in zeromq4-4.0.4 in which fd 0 is treated as
an invalid descriptor.  Implement a workaround to ensure that fd 0
is reopened and not used for anything, for now until we move forward
zeromq4 and get a fix.
Merge pull request #24 from garlick/startup-sync

implement startup synchronization
ubuntu: fix unchecked system() return value

gcc 4.8.2 on ubuntu 14.04 says:

flux.c:401:9: error: ignoring return value of ‘system’, declared with attribute warn_unused_result [-Werror=unused-result]
         (void)system (cmd);
         ^
doc: man page typos, etc.
Merge pull request #26 from garlick/misc-fixes

couple minor tweaks to documentation and one ubuntu compilation issue
build: check for a2x program

Abort configure if a2x is not found.
Fixes issue #4
Merge pull request #27 from garlick/autoconf-asciidoc

build: check for a2x program
fix spelling error in flux-snoop(1)
Merge pull request #28 from garlick/misc-fixes

fix spelling error in flux-snoop(1)