Make #respond_to? calls compatible with Ruby 2.0.0
Make #respond_to? calls compatible with Ruby 2.0.0

devise_invitable relies on respond_to? to decide when to override methods such as #confirmation_required? that may be defined by other Devise modules. In Ruby 2.0, #respond_to? returns false for protected methods unless you pass true as a second method argument. This change in behavior caused 6 test breaks, including delivery of confirmation instructions email after calling #invite! 

Tested with MRI Ruby 1.9.3-p392 and 2.0.0-p0 against mongoid (rake test DEVISE_ORM=mongoid).
scambra/devise_invitable,motephyr/devise_invitable,biow0lf/devise_invitable,kmayer/devise_invitable,mlbileschi/devise_invitable,motephyr/devise_invitable,bonekost/devise_invitable,scambra/devise_invitable,laurelfan/devise_invitable,biow0lf/devise_invitable,mlbileschi/devise_invitable,bold-app/devise_invitable,yakovenkodenis/devise_invitable,laurelfan/devise_invitable,rowanoulton/devise_invitable,kmayer/devise_invitable,bold-app/devise_invitable,yakovenkodenis/devise_invitable,10Pines/devise_invitable,bonekost/devise_invitable,rowanoulton/devise_invitable