Merge pull request #9 from timoschmidt/upstream

Remove "Gem.clear_path" since it is not working in OpsWorks context
adding all options of zkconfigset lwrp in recipe zkconfigets
fix for #7
fix for #8
foodcritic
bump to v0.3.8
updated CHANGELOG
updated README for java tuning parameters
indent fix for attribute file
fixing typo for key_store manage attribute, probable fix for #11
bump version to v0.3.9
Added possiblity to overwrite node attributes that are used as defaults on run time