Improve Application detection and EmberDebug reset.

Fixes #48
Upgrade to Ember RC8
Bump package.json version patch to 0.0.3
Update README to include link to web store
Notify the client application of the extension's existence
Add helpful message when application is not detected.

Design by @sea-jay
Merge pull request #52 from teddyzeenny/not-detected

Add helpful message when application is not detected.
Merge branch 'master' of https://github.com/tildeio/ember-extension