Makes sure Grape::API behaves as a Rack::App

[myxoh]

By calling: 'call' on the first mounted instance rather than the base instance (which is never mounted) which will have the environment information as to where it was mounted

This addresses the underlying issue raised by: #1892

[dblock]

This pollutess the global namespace, put it into a namespace itself?

[myxoh]

In what way @dblock ? I am under the impression that methods defined in a context are contained to that context?

[dblock]

Okay, this is news to me. Since when does it work as one would expect?!

require 'rspec'

describe 'Context' do
  def m1
    'm1'
  end

  it 'is m1' do
    expect(m1).to eq 'm1'
  end

  context 'c1' do
  	def m2
	  'c1:m2'
  	end

    it 'is m1' do
      expect(m1).to eq 'm1'
    end

    it 'is m2' do
      expect(m2).to eq 'c1:m2'
    end
  end

  context 'c2' do
	it 'is m2' do
	  expect(m2).to eq 'c1:m2'
    end
  end
end

  1) Context c2 is m2
     Failure/Error: expect(m2).to eq 'c1:m2'
     
     NameError:
       undefined local variable or method `m2' for #<RSpec::ExampleGroups::Context::C2 "is m2" (./spec.rb:27)>
     # ./spec.rb:28:in `block (3 levels) in <top (required)>'

My bad. Ignore me.