Allow adding of music with no tags

[zachreizner]

We should allow this out of convenience. We can use the file name (sans extension) as the title and leave the rest empty (or some special value indicating that meta data may exist, we just don't know it; this is to disambiguate the cases were we explicitly know the meta data does not exist, in the case of singles which have no track number). Perhaps we should nag users to manually tag music they've uploaded that has missing meta data.
@CJS7070 - I know you were opposed to this and I'd like to make this discussion public rather than hearing it second hand from @kevinwang