Docs update

Signed-off-by: Pierre-Alexandre Meyer <pierre@mouraf.org>
Merge branch 'gh-pages' of github.com:killbill/killbill-docs into gh-pages

Signed-off-by: Pierre-Alexandre Meyer <pierre@mouraf.org>

Conflicts:
	userguide.html
Docs update

Signed-off-by: Pierre-Alexandre Meyer <pierre@mouraf.org>