Introduce a new static method Predicate::not which will allow developers to negate predicate lambdas trivially.
webrev: http://cr.openjdk.java.net/~jlaskey/8050818/webrev/index.html bug: https://bugs.openjdk.java.net/browse/JDK-8050818 csr: https://bugs.openjdk.java.net/browse/JDK-8203428
