Package the logstash into a tarball and can be installed by maven

The following selected folders and files are packaged:
 - /bin/
 - /lib/
 - /locales/
 - /patterns/
 - /spec/
 - /vendor/
 - /tools/
 - /*.rb
 - /*.gemspec

Signed-off-by: Wei Zhang <weiz@logstream.net>