Update design for stream queue

[glennrfisher]

Completed Tasks

• Fix the dividing lines between the videos. Are there two lines? (Go into edit mode and look closely--it looks like there are two lines stacked on top of each other.) Make sure the color matches the design.
• Hide the separator of the current video and the video above it.
• Should say "QUEUE" instead of "UP NEXT".
• Highlight the currently playing video, and set the icon to a play button instead of a number.
• Scroll to the currently playing video when the queue is opened.
• Allow the current video to be deleted.

Deferred Tasks (See #281)

• Number the videos on the left-side.
• Match the color of (-) icon and delete button to the color of the "Add Videos" button.
• Change "Delete" text to "Remove".
• Replace play icon / number with (-) icon when editing (i.e. don't move the thumbnail or text).

[nathan-hekman]

I'd like to discuss the behavior of what should be shown in the queue, using Chromecast with YouTube as a reference.