base

Adds a way to exclude test directories from javadoc.

By adding a file named NO_DOCS to a directory, all
java files under that directory will be ignored for
javadoc builds. This is especially useful for marking
test projects as not participating in the javadoc
build.

Change-Id: I3b0259f4bb3c8460c3560fdcf97c6cac11d8001d