RFR 7116946: JSSecurityManager should use java.util.ServiceLoader to lookup service providers

[Chris Hegarty]

This is a follow up to an issue that came up during discussion of 
another fix. Essentially, JDK classes should use j.u.ServiceLoader 
rather than sun.misc.Service.

http://cr.openjdk.java.net/~chegar/7116946/webrev.00/webrev/

And a few warning cleanups, given the date that's in it ;-) Since 
getProviders is package private I assume it is ok to "generify".

-Chris