7116957: javax.script.ScriptEngineManager 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, ScriptEngineManager should use 
j.u.ServiceLoader rather than sun.misc.Service.

http://cr.openjdk.java.net/~chegar/7116957/webrev.00/webrev/
-Chris.

P.S. and fix up imports in HttpServerProvider