ensure brocfile added deps are added after internal deps

fixes -> https://github.com/stefanpenner/ember-cli/commit/64ee626649aa39943b1ba327c8d8ac4d55e773e3#commitcomment-6189670
Refactor to commands and tasks taking dependencies via constructor options. Paving the way for dependency injection.
Update custom errors instructions
Changes to testem.json

Doesn't run Chrome during CI builds (travis)
Merge pull request #570 from twokul/testem

Changes to testem.json
Use import in test-helpers where possible.
Merge pull request #577 from abuiles/test-imports

Use import in test-helpers where possible.
Update to broccoli 0.10.
Use broccoli's timers for tracking build time.
Merge pull request #578 from rjackson/update-broccoli

Update to Broccoli 0.10.
Swap broccoli-template for broccoli-ember-hbs-template-compiler. Fixes #408
Merge pull request #574 from xtian/precompile-hbs

Add broccoli-ember-hbs-template-compiler. Fixes #408
Update CHANGELOG.md
Add `app.import` to control legacy files, remove broccoli-bower.
better implementation of defaults in `EmberApp`

Lets loader + wrapInEval also be configurable.

We plan soon to make loader configurable via the underlying filter.
Please note, the current setup still does not allow this.
fixes for trees