Only do mix of the day once

Instead of doing it infinitely and usually featuring some mixes more
than others, we should just do it once so that it is fair to everyone.
Add uploads to .gitignore
comment scope undeleted by default

It was a declared scope, which meant most of the time we were selecting
comments that were deleted. This wasn't a problem for displaying them,
but it was showing the unread marker if a comment was posted then
deleted.
allow streaming of a single song
fix likes n+1 query and sort

.count will force a re-query on COUNT(*), but we can use .size which is
smart if there is data loaded already. The sort criteria was also
somewhat arbitrarily changed to be which song's latest like came
earliest. It seemed nicer than sorting by album name.
add libraries for html music player
allow playing mixtapes in browser