Refactor Sidebar Code
Clicking a node refreshes comparison
Sidebar refreshes when empty
disappearing tutorial for new user
Prevent from voting on song under comparison
Merge pull request #49 from taylorharwin/new-sidebar

New sidebar
Add server-side functionality to remove old songs from DB. Add server-side check for file upload size.
Update readme
Added text specifying upload file size limit
Merge pull request #51 from gnauhnoj/JonDev2

Server Changes
Update D3 to handle colors based on cache status. Update D3 to use linear scaling for volume.
Merge pull request #52 from gnauhnoj/dev

D3 Changes for Cache Status