Download JAR files tagged by retrolambda with all dependencies

Basic Java 8 archetype. Options: -testLibrary: [junit, testng, none]. DEFAULT: junit. Adds the requested test library to the POM deps. -compilerMode: [simple, test-only, retrolambda-main, retrolambda-all]. DEFAULT: simple. --simple: everything is compiled as Java 8. --test-only: set up test for Java 8, and main for Java 7. --retrolambda-main: main code is compiled as Java 8, and then converted to Java 7 via retrolambda. --retrolambda-all: all code is compiled as Java 8, and then converted to Java 7 via retrolambda. NOTE: Retrolambda support provided "as is" - if you have any problems, please file a ticket on the GitHub page!