Mailman bundler howto should include instructions on installing sassc
In reference to hyperkitty#24 (comment 2747455), I want to point out that https://mailman-bundler.readthedocs.org/en/latest/ does not include instructions for installing
sassc. Under Debian I found no way of doing so using the package manager and had to
make install both https://github.com/sass/libsass and https://github.com/sass/sassc.