Merge branch 'release/3.9.0'
Merge branch 'release/3.9.1'
bump selenium-webdriver to overcome a loading error for rubyzip

Previously, creating a new ckit project would result in the following error:

  selenium-webdriver-2.29.0/lib/selenium/webdriver/common/zipper.rb:1:in
'require': cannot load such file -- zip/zip (LoadError)
Merge branch 'master' of git://github.com/saturnflyer/chemistrykit into develop
added contribution clarity to readme docs
updated rubo and fixed some code quality issues
locked ruby version until clearing up how that can be managed