Enable local filepaths for testing.

If the template_url is actually an absolute path, then read the
template from there. This provides for testing local changes to the
templates without having to commit them. (normally, svnauthz always
reads committed templates from github.com)

authz.py

@@ -108,8 +108,12 @@ def write_files(self):
         if self.debug:
             print('WRITE_FILES: beginning at', t0)
         for t, o in self.mappings.items():
-            template = requests.get(t, auth=self.auth, timeout=30)
-            self.gen.write_file(template.text.splitlines(), o)
+            if t.startswith('/'):
+                # File path. Just read it.
+                template = open(t).read()
+            else:
+                template = requests.get(t, auth=self.auth, timeout=30).text
+            self.gen.write_file(template.splitlines(), o)
         if self.debug:
             print(f'  DURATION: {time.time() - t0}')