De-couple scene id needed for "begin" link from text entered on scene description

[Logodaedalus]

Currently, if you want to start a scene in timeline view, you have to make sure in the scene's config field "descriptionText" you have a link like this:

<a href='#' class='beginScene' id='begin-testScene2'>Begin Scene</a>

At the very least, we should only require that a link with 'beginScene' class is in it...setting the id of the scene to begin off the text value of the link's id (Display.js:606) is...horrible.