Add hooks for running linters and tests

Add the `scripts/setup-hooks.sh` script which sets the following hooks
up:
- The `post-commit` hook runs the linter after every `git commit`,
  letting you know if there are code style or rule linter offenses you
  need to fix.
- The `pre-push` hook runs the linter and the tests and block the `git
  push` if they do not succeed.
  This way you realise if everything is alright without the need of
  sending a PR.

scripts/hooks/post-commit

@@ -0,0 +1,34 @@
+
+# Use a console with emojis support for a better experience
+
+# Stash uncommited changes
+MSG="post-commit-$(date +%s)"
+git stash push -kqum $MSG
+STASH_LIST=$(git stash list)
+if [[ "$STASH_LIST" == *"$MSG"* ]]; then
+  echo "Uncommited changes stashed with message '$MSG', if you abort before they are restored run \`git stash pop\`"
+fi
+
+# Run style checker and print state (it doesn't block the commit)
+pycodestyle --config=./ci/tox.ini ./capa/ > style-checker-output.log 2>&1
+if [ $? == 0 ]; then
+  echo 'Style checker succeeds!! 💘'
+else
+  echo 'Style checker failed 😭\nCheck style-checker-output.log for details'
+  exit 1
+fi
+
+# Run rule linter and print state (it doesn't block the commit)
+python ./scripts/lint.py ./rules/ > rule-linter-output.log 2>&1
+if [ $? == 0 ]; then
+  echo 'Rule linter succeeds!! 💖'
+else
+  echo 'Rule linter failed 😭\nCheck rule-linter-output.log for details'
+  exit 2
+fi
+
+# Restore stashed changes
+if [[ "$STASH_LIST" == *"$MSG"* ]]; then
+  git stash pop -q --index
+  echo "Stashed changes '$MSG' restored"
+fi