Should we rename the MASTER forest?

[Mark Reinhold]

The consensus amongst existing contributors was in favor of renaming
the MASTER forests as proposed, so I've gone and done that.

Effective immediately please replace all URLs of the form

    http://hg.openjdk.java.net/jdk7/MASTER

with

    http://hg.openjdk.java.net/jdk7/jdk7 ,

and similarly replace "MASTER-GATE" with "jdk7-gate".

- Mark