= io: quiet down exceptions from `Socket.shutdownOutput()`, fixes #468

It seems older versions (< 7) of the JDK have a condition where
`shutdownOutput` can fail:

http://bugs.sun.com/view_bug.do?bug_id=4516760

This is a workaround that catches the exception and views the connection
as closed if the exception occurs.
Merge pull request #469 from jrudolph/i/468/quiet-shutdownOutput

= io: quiet down exceptions from `Socket.shutdownOutput()`, fixes #468