Implemented support for multiple installed versions.

Improved testing, including multiple installed versions.

Replaced problematic "start_broken_java" test (which failed by finding
Java anyway on the Mac!) with a test that handles an activemq which
won't come up for any reason.

Added support for current versions of ActiveMQ.

Added support for downloading historical ActiveMQ versions.

Added README.

Incremented version numper in preparation for release.
Merge pull request #1 from laufeyjarson/script

LGTM!