Proposal/add pre commit

[Moep90]

Why?

I found to have these kind of pre-commits very useful. In my team we're even more strict with them.
I guess its a good starting point which we may extend to be used with automatic documentation, like you wrote here already: #1

NOTE:

Merge #87 first

Initial changes

pre-commit run --all-files
Trim Trailing Whitespace.................................................Failed
- hook id: trailing-whitespace
- exit code: 1
- files were modified by this hook

Fixing compiled/gke-pvm-killer/docs/README.md
Fixing inventory/classes/kapitan/common.yml
Fixing compiled/tesoro/scripts/generate_tesoro_certs.sh
Fixing inventory/classes/components/mysql.yml
Fixing inventory/classes/components/filebeat.yml
Fixing compiled/pritunl/docs/README.md
Fixing components/mysql/mytemplate.cnf.j2
Fixing compiled/postgres-proxy/docs/README.md
Fixing inventory/classes/features/gkms-demo.yml
Fixing compiled/dev-sockshop/docs/README.md
Fixing compiled/tesoro/docs/README.md
Fixing templates/scripts/generate_tesoro_certs.sh
Fixing compiled/global/README.md
Fixing inventory/classes/features/tesoro.yml
Fixing inventory/classes/components/echo-server.yml
Fixing components/generators/kubernetes/README.md
Fixing inventory/classes/components/kapicorp/tesoro.yml
Fixing compiled/prod-sockshop/docs/README.md
Fixing templates/docs/README.md
Fixing compiled/examples/docs/README.md
Fixing compiled/tutorial/docs/README.md
Fixing compiled/global/docs/README.md
Fixing compiled/sock-shop/docs/README.md
Fixing templates/docs/global/README.md
Fixing compiled/echo-server/docs/README.md
Fixing compiled/mysql/docs/README.md

Check docstring is first.................................................Passed
Check JSON...............................................................Passed
Check Yaml...........................................(no files to check)Skipped
Debug Statements (Python)................................................Passed
Tests should end in _test.py.........................(no files to check)Skipped
Fix requirements.txt.................................(no files to check)Skipped
Fix double quoted strings................................................Failed
- hook id: double-quote-string-fixer
- exit code: 1
- files were modified by this hook

Fixing strings in components/generators/kubernetes/k8s.py

Check for merge conflicts................................................Passed

After fixing/updating the files

pre-commit run --all-files
Trim Trailing Whitespace.................................................Passed
Check docstring is first.................................................Passed
Check JSON...............................................................Passed
Check Yaml...........................................(no files to check)Skipped
Debug Statements (Python)................................................Passed
Tests should end in _test.py.........................(no files to check)Skipped
Fix requirements.txt.................................(no files to check)Skipped
Fix double quoted strings................................................Passed
Check for merge conflicts................................................Passed