Generate man pages from asciidoc

Working directly with g/roff is a pain.
Also changed the formatting of toxic.conf.5 a bit.

Signed-off-by: Loui Chang <louipc.ist@gmail.com>
Remove old man pages.

Signed-off-by: Loui Chang <louipc.ist@gmail.com>
Add Asciidoc to README and travis

Signed-off-by: Loui Chang <louipc.ist@gmail.com>
Add generated man pages.

Signed-off-by: Loui Chang <louipc.ist@gmail.com>
Make asciidoc 'optional'

Run `make doc` in the build directory after editing the asciidoc to
regenerate the manpages. Changes to asciidoc source and generated man
pages will need to be commited together.

Signed-off-by: Loui Chang <louipc.ist@gmail.com>
doc: Make asciidoc extra optional.

Completely separate man page generation from the main build to satisfy
travis-ci behaviour.

Signed-off-by: Loui Chang <louipc.ist@gmail.com>
Merge pull request #230 from louipc/manpage

Manpage