Fixes `make install` to not create a ./bin directory
replace ronn by md2man

ronn is unmaintained since 2 years and it's dependency, hpricot doesn't
install anymore on ruby2+ on OSX.

Both suffer from the bug described in #113 but at least md2man is going to
be fixed. See sunaku/md2man#18
Doc updates
Fixes lintian warning
Merge branch 'md2man'