Configurable dirty-checking behavior

[jdanyow]

Note: this issue originated in aurelia/framework#386 read the comments there first

Enable developers to decide what Aurelia should do when observing a property will require dirty-checking.

Questions/considerations:

• What is the API for configuring the dirty-checking behavior? Consider ability to add logging info when binding to non-existent properties #30 when thinking about the config API.
• What behaviors/options do we ship? log/throw
• PR requires documentation and tests.
• Breaking changes must be avoided.
• Related issue: Pause and restore dirty checking using page visibility API #562

[atsu85]

What behaviors/options do we ship? log/throw

just choosing between logging/throwing isn't good enough - I'd like to replace the handler, so i'd be able to show UI message, send notification to Bugsnag and throw an error (as I've done when aurelia-computed has discovered a getter, where dependencies can't be computed by aurelia-computed plugin, resulting in fallback to dirty-checking)