Don't push code coverage when on hhvm environment.

Signed-off-by: crynobone <crynobone@gmail.com>
\Orchestra\Debug\Profiler::extend() should return $this.

Signed-off-by: crynobone <crynobone@gmail.com>
sort use order

Signed-off-by: crynobone <crynobone@gmail.com>
Merge branch '2.1' into 2.2