constrain sinatra to ~> 1.3.2

Sinatra 1.4.3 gives the following error:

    ==> /var/vcap/sys/log/cloud_controller_ng/cloud_controller_ng.stderr.log <==
    /var/vcap/packages/cloud_controller_ng/cloud_controller_ng/vendor/bundle/ruby/1.9.1/gems/sinatra-1.4.3/lib/sinatra/base.rb:1533:in `block in compile!': undefined method `consumes' for VCAP::CloudController::Controller:Class (NoMethodError)
        from /var/vcap/packages/cloud_controller_ng/cloud_controller_ng/vendor/bundle/ruby/1.9.1/gems/sinatra-1.4.3/lib/sinatra/base.rb:1533:in `each_pair'
        from /var/vcap/packages/cloud_controller_ng/cloud_controller_ng/vendor/bundle/ruby/1.9.1/gems/sinatra-1.4.3/lib/sinatra/base.rb:1533:in `compile!'
        from /var/vcap/packages/cloud_controller_ng/cloud_controller_ng/vendor/bundle/ruby/1.9.1/gems/sinatra-contrib-1.4.0/lib/sinatra/reloader.rb:253:in `compile!'
        from /var/vcap/packages/cloud_controller_ng/cloud_controller_ng/vendor/bundle/ruby/1.9.1/gems/sinatra-1.4.3/lib/sinatra/base.rb:1515:in `route'
        from /var/vcap/packages/cloud_controller_ng/cloud_controller_ng/vendor/bundle/ruby/1.9.1/gems/sinatra-1.4.3/lib/sinatra/base.rb:1352:in `post'
Merge pull request #54 from drnic/constrain_sinatra

restrict sinatra to 1.3.X family; otherwise get - undefined method `consumes' for VCAP::CloudController::Controller:Class