removed warning for @failed

refactoring @failed and failed? methods to remove ruby warnings
removed warning: assigned but unused variable

refactored variables use in gherkin_builder.rb so that we don't have
assigned but unused variables
rmv  warning: assigned but unused variable - e

small refactoring to removed  warning: assigned but unused variable - e
rmv unused variables in rb_language.rb

removed unused variables in lib/cucumber/rb_support/rb_language.rb:54
and :62 to give better performance and remove ruby warnings
removed unused variables in rb_world.rb

removed unused variable 'e', we were  passing the exception and the the
backtrace into variable 'e' but we were not using it. It was not memory
efficient .
refactor method because @features may not be defined

refactor method because @features may not be defined and would reflect
in warning: instance variable @features not initialized.
refactor, removed unused variables and warnings

refactor, removed unused variables and warnings for initialized
variables
Merge pull request #342 from cjapes/master

refactor unused variables and initialized variable warnings