Create inexistent paths in standardpath.get.

See #25.

qutebrowser/utils/standarddir.py

@@ -86,8 +86,7 @@ def get(typ, args=None):
               locations.
     """
     overridden, path = _from_args(typ, args)
-    if overridden:
-        return path
+    if not overridden:
         path = _writable_location(typ)
         appname = QCoreApplication.instance().applicationName()
         if (typ == QStandardPaths.ConfigLocation and
@@ -103,6 +102,8 @@ def get(typ, args=None):
                 QStandardPaths.ConfigLocation)
             if data_path == config_path:
                 path = os.path.join(path, 'data')
+    if not os.path.exists(path):
+        os.makedirs(path, 0o700)
     return path