Fixes to make_javadoc.sh script

Three changes: BROOKLYN_VERSION annotation to ensure that 0.7.0-SNAPSHOT
reference is updated. Javadoc output spews out a lot of noise to stdout
and errors/warnings to stderr, but use of 'tee' saves only stdout noise
and not the useful error messages - changed to send errors to stdout,
and what was stdout goes to /dev/null. Finally, abort if the required
brooklyn-all-dependencies jar file has not been built.