aurelia-binding v0.9.0

Bug Fixes

• BindingExpression: remove needless check for undefined (afcc1ef3)
• OoObjectObserver: unsubscribe leak (9818841c)
• ValueAttributeObserver: set undefined/null to empty string (e18b1f60, closes #152)
• build: update linting, testing and tools (dbb5d08b)

Features

• docs:
  • generate api.json from .d.ts file (6aa3caaa)
  • generate api.json from .d.ts file (e612055f)