POC: require explicit bindings for core+plugins

The requireExplicitBindings option can help find broken/incorrect bindings by turning off "just-in-time" bindings: https://code.google.com/p/google-guice/wiki/JustInTimeBindings. This is especially useful when working with private modules or child injectors, where any "just-in-time" bindings bubble up to the parent injector causing potential binding clashes at runtime.

Also verify latest Guice build (3.2.2) which includes various fixes and support for Java8.

http://google-guice.googlecode.com/git/latest-api-diffs/3.0/javadoc/com/google/inject/Binder.html#requireExplicitBindings()