#446 pluginloader does not load libs from plugin_paths
The pluginloader only loads modules from plugin_paths, not libs.
That results in, for example, ldap.lib.lua not being found when loading mod_storage_ldap from prosody-modules and not copying it to CONF_PLUGINDIR.
pluginloader loads libs from the current modules directory, but ldap.lib.lua is not found in eg mod_storage_ldap/. This can be worked around by doing module:require("mod_lib_ldap/ldap"), but improving this would be nice.