Add skeleton for photo booth page
Basic video capture working

NB this rotates the video element on Tizen, otherwise it
appears incorrectly rotated when locked to landscape.

Unsure if this is a bug or intended behaviour, but leaving it for
now.
Snapshot workflow foundations in place

Working for Tizen and Chrome, but doesn't dump the video to
the canvas element yet.
Add snapshot taking (not saving yet)
Get blob from canvas
Add save to filesystem
Hide photobooth page by default
'Take a photo' button remains disabled if webcam has no permissions
Formatting cleanup for consistency