Some memory optimizations

The projects are actually removed now when all clients in a room leave. It's on a 5 second timer after the last person leaves to finish any pending writes. They usually take nano-to-milli seconds to write to the project, but it doesn't hurt to be conservative just in case.

When someone joins an already created room, the server now sends the project that it has in memory to the new client instead of hitting the database. That was wasteful extra hits to the database and I can't remember my initial reasoning for always hitting the database unless it was just a TODO that I forgot to add to the comments.

This addresses issue #112.

Removed unused file src/static/js/canvas.js from issue #113.