Remove Sinatra's scope specific switching
Remove Sinatra's scope specific switching

There is no need to fetch the views path from `scope` any more because it
is passed via `:view_path` option now, and fetching it is not recommended
because `scope` passed from Sinatra can be non-Sinatra-application instance
like below:

    jbuilder :hello, :scope => Object.new

linchus/tilt-jbuilder,joneslee85/lotus-jbuilder,anthonator/tilt-jbuilder,nazipov/tilt-jbuilder