Revert "Replace deprecated ConfigParser method"

This reverts commit de1d06e33c. It breaks
running with python2.7

tuir/config.py

@@ -250,7 +250,7 @@ class Config(object):
         config = configparser.ConfigParser()
         if os.path.exists(filename):
             with codecs.open(filename, encoding='utf-8') as fp:
-                config.read_file(fp)
+                config.readfp(fp)
 
         return cls._parse_tuir_file(config)
 

tuir/theme.py

@@ -399,7 +399,7 @@ class Theme(object):
             config = configparser.ConfigParser()
             config.optionxform = six.text_type  # Preserve case
             with codecs.open(filename, encoding='utf-8') as fp:
-                config.read_file(fp)
+                config.readfp(fp)
         except configparser.ParsingError as e:
             raise ConfigError(e.message)