Added Warbler to create Java jar files

- configuration file for warbler created in config directory
- added warbler gem to the development group in the Gemfile, due to a bug we need to use the latest version of Warbler from GitHub for now
- updated Gemfile.lock
Updated Readme with information on building Java jar files
Updated installation information in Readme
Merge pull request #45 from ffeldhaus/master

Added Warbler to create Java jar files