This PR uses a new Karma plugin to enable vendor bundles in unit tests,
increasing rebuild performance.
On a medium size project rebuilds times were 15x smaller (16.5s to 0.9s).
Fix#5423
Removes the warning that would appear on new projects when running `ng test` due to there being no files inside `src/assets/`:
```
23 02 2017 10:45:33.751:WARN [watcher]: Pattern "D:\sandbox\master-project\src\assets/**" does not match any file.
```