Add basic-auth handler using lua-pwauth simple password authentication

Includes an example utilising pwauth.pam and a sketchup for pwauth.sasl that still lacks the backend in lua-pwauth.
Bump lua-pwauth from easier building against luajit
Bump lua-pam for changed internals (no changes affecting moonslice-luv)
Do not limit-to-path in the basic-auth module - use path-filter for that
Merge pull request #11 from devurandom/feat/basic-auth

Add basic-auth handler using lua-pwauth simple password authentication