Added vfsStream to require-dev. Tests for extend fn within Project.
Merge branch 'master' of https://github.com/taskphp/task into feature/extend-tests

* 'master' of https://github.com/taskphp/task:
  Add coveralls
  Use CI phpspec config in travis.yml

Conflicts:
	composer.json
Merge pull request #3 from KashifSaadat/feature/extend-tests

Feature/extend tests