Add capability to ask for desired permissions from linked in api

    Add capability so that appropriate permissions can be requested as below:

    client = LinkedIn::Client.new('your_consumer_key', 'your_consumer_secret')
    request_token = client.request_token(
      {:oauth_callback => "http://#{request.host_with_port}/auth/callback"},  :scope => "rw_nus"
    )

    session[:rtoken] = request_token.token
    session[:rsecret] = request_token.secret

    redirect_to client.request_token.authorize_url