RFR: 7178362: Socket impls should ignore unsupported proxy types rather than throwing

[Seán Coffey]

This issue relates to another bug that I own : JDK-8062305

It seems to be an area that causes alot of issue (for plugin mainly) and 
the suggestion from Chris in 7178362 bug report to return a direct 
connection type for bad ProxySelector implementations seems appropriate.

webrev : http://cr.openjdk.java.net/~coffeys/webrev.7178362/webrev/
bug report : https://bugs.openjdk.java.net/browse/JDK-7178362

regards,
Sean.