- Move connection data to separate transport class, in addition to current, direct connection via WS, also support sending screencast data via redis pubsub
- Implement WSTransport and RedisPubSubTransport for screencasting
- Redis screencasting enabled when --redisStoreUrl is set and --screencastRedis is set.
- Redis screencasting uses pubsub channels:
* a ctrl channel is used to start/stop screencasting
* a data channel is used to send screencast messages
Simplify screencasting messages:
{"msg": "screencast", "id": "<page id>", "url": "<page url>", "data": "<png base64 data>"} - for new and incremental screencast frames for page id
{"msg": "close", "id": "<page id>"} - to indicate page id has closed.
Rename html dir from screencast -> html
