Fix configtypes mistakes

qutebrowser/config/configdata.yml

@@ -507,11 +507,11 @@ content.custom_headers:
   type:
     name: Dict
     keytype:
-      - name: String
-      - encoding: ascii
+      name: String
+      encoding: ascii
     valtype:
-      - name: String
-      - encoding: ascii
+      name: String
+      encoding: ascii
     none_ok: true
   desc: Set custom headers for qutebrowser HTTP requests.
 

qutebrowser/config/configtypes.py

@@ -1122,7 +1122,7 @@ class Padding(Dict):
     def __init__(self, none_ok=False, valid_values=None):
         super().__init__(keytype=String(), valtype=Int(minval=0),
                          fixed_keys=['top', 'bottom', 'left', 'right'],
-                         none_ok=none_ok, length=4)
+                         none_ok=none_ok)
         # FIXME:conf
         assert valid_values is None, valid_values