Two unrelated changes: A failed ICAP RESPMOD transaction could leave

	Two unrelated changes: A failed ICAP RESPMOD transaction could leave
	the HTTP transaction stuck and a bug #1819 fix.

	Change 1: After detecting an ICAP error and calling fwd->fail(),
	the HTTP Server now calls abortTransaction() (and, hence,
	comm_close) instead of calling closeServer() (and, hence,
	fwd->unregister).  Server::closeServer() is a virtual method
	that should not be called outside of Server::serverComplete().
	It would be nice to enforce that somehow. Perhaps we should at
	least rename closeServer?

	Change 2: Bug #1819 fix: retry the ICAP transaction when its
	pconn fails. The changes in this file were minor. Search
	src/ICAP/ICAPXaction.cc log around v1.7 for complete details of
	the bug #1819 fix.