v0.7.0

Changelog:

• Add support for custom user messages in WebSocket handlers. The on_init function now receives a process.Selector that can be used to listen for custom messages sent from other parts of the application.
• Custom messages are delivered to WebSocket handlers as ewe.User(message) type.
• Add permessage-deflate compression support for WebSocket connections. When enabled, messages are automatically compressed using defalte algorithm, reducing bandwidth usage for text-heavy applications.