Added code to reject PUT requests to directories.
Added code to reject PUT requests to directories.

evWork/nds-server,nicola/ldnode,linkeddata/ldnode,dmitrizagidulin/solid-server-unstable,deiu/ldnode,deiu/ldnode,dmitrizagidulin/solid-server-unstable,timbl/ldnode,timbl/ldnode,evWork/nds-server,dmitrizagidulin/solid-server-unstable,martinmr/node-ldp-httpd,linkeddata/ldnode,evWork/nds-server,nicola/ldnode,martinmr/node-ldp-httpd