don't use Blockly at all on editCode levels

Previously, editCode levels still kept a div around called Blockly, loaded the blockly-core vendor.js, and injected Blockly into the page (while keeping it hidden).

I cleaned this up now so BlocklyApps.usingBlockly is the opposite of BlocklyApps.editCode and we only do Blockly things inside BlocklyApps.usingBlockly.
It's a good idea, though I'm not certain that we want to have this at the @game level in the long run (since it is really already stored on the level inside blockly). So I've been loathe to introduce a db schema change on Game until we come up with the right model. Note that in the node.js server we use a completely different mechanism (and even more hacky) to decide.