Merge in changes from master.  Undo the changes to require Java 6 and re-introduce some of the Java 7 examples.
Merge pull request #51 from DavidWhitlock/java-7

Allow Java 7 language level because all of the student have at least Java 7.
Merge branch 'master' into java-8

Conflicts:
	grader/src/main/java/edu/pdx/cs410J/grader/Submit.java
	pom.xml