Changed the registerNodeTypeCnd to have allowUpdate parameter
Changed the registerNodeTypeCnd to have allowUpdate parameter

The new parameter on registerNodeTypeCnd makes sure that a note
type will not accidentially overwritten, because an exception
is thrown, when the flag is set to false and the node type already
exists.

rederrik/phpcr-api-tests,richard-fizz/phpcr-api-tests,danrot/phpcr-api-tests