Adds remove-tabs hook

Inpired by initial work done by Lucas-C:
https://github.com/Lucas-C/pre-commit-hooks

pre_commit_hooks/remove_tabs.py

@@ -0,0 +1,53 @@
+from __future__ import print_function
+
+import argparse
+import sys
+from typing import Any
+
+
+def contains_tabs(filename):  # type: (str) -> bool
+    with open(filename, mode='rb') as file_checked:
+        return b'\t' in file_checked.read()
+
+
+def removes_tabs_in_file(filename, whitespaces_count):
+    # type: (str, int) -> None
+    with open(filename, mode='rb') as file_processed:
+        lines = file_processed.readlines()
+    lines = [line.replace(b'\t', b' ' * whitespaces_count) for line in lines]
+    with open(filename, mode='wb') as file_processed:
+        for line in lines:
+            file_processed.write(line)
+
+
+def main(argv=None):  # type: (Any) -> int
+    parser = argparse.ArgumentParser()
+    parser.add_argument(
+        '--whitespaces-count', type=int, required=True,
+        help='number of whitespaces to substitute tabs with',
+    )
+    parser.add_argument('filenames', nargs='*', help='Filenames to fix')
+
+    args = parser.parse_args(argv)
+
+    return_code = 0
+    for filename in args.filenames:
+        if contains_tabs(filename):
+            print('Substituting tabs in: {} by {} whitespaces'.format(
+                filename, args.whitespaces_count,
+            ))
+            removes_tabs_in_file(filename, args.whitespaces_count)
+            return_code = 1
+
+    if return_code:
+        print('')
+        print('Tabs have been successfully removed. Now aborting the commit.')
+        print(
+            'You can check the changes made. Then simply '
+            '"git add --update ." and re-commit',
+        )
+    return return_code
+
+
+if __name__ == '__main__':
+    sys.exit(main())