Increase kill timeout on kafka shutdown

On heavy loaded kafka brokers 20 seconds are not enough for a clean
shutdown. Timeout increased to 60 seconds.

Change-Id: I5441a1c5eddf33e1bdf5d7a0905017629e60cf13
Use generic snappy version and fix CLASSPATH

Change snappy-java-1.0.4.1.jar to snappy-java.jar and remove duplicate
slf4j-api.jar in bin/kafka CLASSPATH definition.
Remove same duplicate in debian/rules and fix a typo.