Implement cookie DSL
Remove ActionBuilder.withNext, pass next on build
Simplify action names
Introduce Chainable so Action don' require next, delete BypassSessionHookBuilder
Remove useless scalaz import
Make UserStart Chainable
Minor clean up
Fix param/multiValuedParam(String)
Remove ChainBuilder.withNext
Merge pull request #903 from excilys/cookie-dsl

Cookie dsl, close #899