use start_cluster rake task for elastic test

This will allow for a longer bootup-time before
a timeout.
add a script to rebuild ontohub in development.
add invoker-support to rebuild script

This includes aborting if invoker ist not installed and
restarting a running invoker instance, or starting a new
one if no one was running before.
Merge pull request #1129 from ontohub/fix-ease_of_use

Fix ease of use