Update 2015-07-17-sparkberry-pi.markdown
Update 2015-07-17-sparkberry-pi.markdown

This tutorial was updated to
- resolved issues with classloader.
- documented new installation process for groovy.
- updated Spark version.
- added slf4j logging.
sparkjava/sparkjava.github.io,sparkjava/sparkjava.github.io,sparkjava/sparkjava.github.io,sparkjava/sparkjava.github.io