#1727 shutdown WebConnectionWrapper to clear wrapped web connection

[standlove]

When using a custom WrappedWebConnection, the inner HttpWebConnnection is never closed properly.

Can you fix this bug by adding the following stuff in the next version:
1. Add a shutdown method in WebConnection interface.
2. In WebClient's close method, call webConnection.shutdown() directly. So if it's a instance of WrappedWebConnection, the inner web connection is closed properly.

Thanks.

[Ahmed Ashour]

The proposed solution is to let WebConnection extend AutoCloseable. and to .close() it from WebClient.close().

@Others: any objection?

[Ahmed Ashour]

Thanks for reporting, fixed in SVN.