Enable pre-commit tool linting

This should help use keep the codebase more consistent, and avoid sevel
whitespace related issues, or bad file permissions.

pre-commit allows us to easily introduce other linters in follow-ups,
like bashate.

Note: pre-commit tool does *not* install any git-hooks. Making commits
will will call the tool unless you deliverately tell it to install the
hooks.

Signed-off-by: Sorin Sbarnea <ssbarnea@redhat.com>

.pre-commit-config.yaml

@@ -0,0 +1,12 @@
+---
+exclude: ^vendor/
+repos:
+  - repo: https://github.com/pre-commit/pre-commit-hooks.git
+    rev: v2.4.0
+    hooks:
+      - id: end-of-file-fixer
+      - id: trailing-whitespace
+      - id: mixed-line-ending
+      - id: check-byte-order-marker
+      - id: check-executables-have-shebangs
+      - id: check-merge-conflict