Add a parser for harmless fileformats

src/harmless.py

+from . import abstract
+
+class HarmlessParser(abstract.AbstractParser):
+    mimetypes = {'application/xml', 'text/plain'}
+
+    def __init__(self, filename: str):
+        self.filename = filename
+        self.output_filename = filename
+
+    def get_meta(self):
+        return dict()
+
+    def remove_all(self):
+        return True