Fix handling of angle brackets in mod_muc_log when outputting plaintext

Previously, nicks surrounded by angle brackets (see Nick2 on line 323)
were being lost when outputting plaintext, because htmlize() was ignoring
them then fw() was stripping them as HTML tags.
Support middleware and module option configuration in ejabberd_cowboy
Example config for running a static file web server

This should provide equivalent functionality to mod_http_fileserver in
P1 ejabberd.