cmbd: fix -k option parsing segfault

Need to add a colon suffix in getopt or we get segfault using -kN
as opposed to --k-ary=N.
flux-start: add -o option, drop -k option

Allow passing of arbitrary options to the cmbd using -o.
Example:  flux start -o"-v,-k4"

Drop the -k-ary option which now can be specified this way.
flux-start: drop -M, -O options

Modules can be loaded dynamically via 'flux module load',
or the new -o option can be used to pass module options to cmbd.
Therefore, drop the module options from flux-start.
cmbd: rework module args

Add to the list of modules to load by repeating -Mname option.
name can be suffixed with a nodeset, as before, e.g. -Mjob[0].
Multiple modules cannot be passed in a single option.

Move module options from non-option arguments to -O option, also
specified multiple times, e.g. -Okvs:foo=bar -Okvs:a=b.

This should allow modules and options to be more easily passed from
flux-start(1) and similar using its -o option, e.g.
    flux-start -o"-Mkvs,-Okvs:foo=bar,-Mlive"
cmbd: add --quiet option

fixes issue #31
doc: update flux-start(1) options description
doc: add cmbd(1) man page
cmbd: add missing longopts[] entry for --quiet
Merge pull request #39 from garlick/command-args

simplify flux-start options