implemented pre-push-hook

implemented pre-push hook for git.
to test run:
1.  grunt install:hooks
2.  chmod +x .git/hooks/pre-push

- [x] test coverage
- [x] finish the code
- [ ] gather feedback for my changes
- [ ] submit changes to the documentation


| Q             | A
| ------------- | ---
| Bug fix?      | yes
| New feature?  |yes
| Tests pass?   | none
| Fixed tickets | none
| Doc           | none

finished but should not be merged!