This changes the parser_help command to a lambda which passes
the parser variable to the usage() function as a second
parameter.

We forgot to give the usage() function its "parser" parameter,
and after we moved the definition of the parser variable out
of the main module, the usage() function did not see the parser
variable any more.

Rpm can be bitchy, but also return 0, so handle that.  Also try to do
something meaningful / useful with the error output.

Move module imports of the fedora_cert, koji, and pyfedpkg
modules to the actual command runtime.

This gets rid of the requirement to have them (and their
respective imported modules) installed at build time for
generating the man page.

Move actual man page generation call from Makefile.am
to the src/fedpkg_man_page.py __main__ section.

Move location/name of man_page module (out of the
pyfedpkg module/namespace) in order to avoid
importing pyfedpkg for man page generation.

This apparently disappeared in commit 582c0e69.