updating readme with information about async tests
Merge pull request #50 from Emerson/master

Updating readme with information about async tests
add some more notes about async testing/promises
fix npm install errors for karma-qunit and qunit
Merge pull request #67 from fivetanley/fix-npm

fix npm install errors for karma-qunit and qunit
Fixed `this.$(selector)` returning cached result

Existing usage of `this.$()` will continue to function the same way, while
`this.$(selector)` will work similarly to `this.subject().$(selector)` but
will first ensure that the subject has been rendered.

Also deprecated `this.append()` in favor of its new name, `this.render()` to
help better communicate its purpose.

Fixes #55.