Created script to aggregate return status

- See travis-ci/travis-build#67
- Aggregates return status for each command, and exits with non-zero status if
  any single command has a non-zero status
Merge commit 'refs/pull/3649/head' of github.com:zendframework/zf2 into hotfix/travis-build
Merge pull request #3649 branch 'hotfix/travis-build'