981311 - fix nested constraints with match routes

Due to bug in Rails, this code:

    scope :module => :v2, :constraints => ApiVersionConstraint.new(:version => 2) do
      match '/systems' => 'systems#activate', :via => :post, :constraints => RegisterWithActivationKeyContraint.new
    end

causes the version 2 of systems#activate to be used, even the version
2 is no specified in headers (the nested constraints are not combined
when using with match.

This code works as expected:

    scope :module => :v2, :constraints => ApiVersionConstraint.new(:version => 2) do
      scope :constraints => RegisterWithActivationKeyContraint.new do
        match '/systems' => 'systems#activate', :via => :post
      end
    end
Merge pull request #2590 from iNecas/bz/981311

981311 - fix nested constraints with match routes