Refactoring

Wrote a separate function that returns the (canonical) path to the
creole directory, so that this code can be tested.  (It was in the
function elwiki/site-header-or-footer).
Added elwiki/send-site-header-or-footer test

Added test for elwiki/send-site-header-or-footer, which fails, even
though the function seems to be correct.  I suspect the way fakir is
used is wrong.