RFR: refactorings for Java 5 and 7 features

[Brian Goetz]

As part of a code cleanup effort, we're updating our codebase to take 
advantage of features added in previous Java versions, which we haven't 
been as good about as we'd like.  This is a first batch of changes, but 
won't be the last.

For this batch, I've mostly restricted myself to those that can be 
automatically detected and fixed using IntelliJ, though some were done 
manually because they required more complex restructuring.

The webrev:
   http://cr.openjdk.java.net/~briangoetz/JDK-8030245/webrev/

has proposed changes for JDK-8030245 (try-with-resources and 
multi-catch), JDK-8030253 (strings in switch), and JDK-8030262 (foreach 
loops).