Moved the original PermuteParens.java to a Java8 version, in preparation for simplifying the original to a Java 7 version suitable for posting on CareerCup. Note that the Java8 version had extra stuff that was really only to test out Java 8 features.
Created simplified version of PermuteParens.java for posting on CareerCup. Could simplify even further by dispensing with the tree building, simply outputting desired results in a single traversal.