Container bundling features

[mweidner037]

• Way to report metadata for containers (author, license, etc., like in package.json).
• "Standalone" field, indicating whether it is a standalone file, thus downloadable (with guarantee of working) and sandboxable. E.g. multi-file horse demo is not standalone.
• Option to load containers from zip file, sending index.html first and then the assets, so that you can bundle all assets but still load quickly (e.g. horse demo standalone).
• Sync container titles throughout (in case it changes dynamically). Likewise with icons.

[mweidner037]

#253