Revert "Add global "locale" config option"

This reverts commit 9e90c77, because it caused a bug that affected
different people just after being released:
https://github.com/adrienverge/yamllint/issues/285
https://github.com/adrienverge/yamllint/issues/286

yamllint/config.py

@@ -35,8 +35,6 @@ class YamlLintConfig(object):
         self.yaml_files = pathspec.PathSpec.from_lines(
             'gitwildmatch', ['*.yaml', '*.yml', '.yamllint'])
 
-        self.locale = 'C.UTF-8'
-
         if file is not None:
             with open(file) as f:
                 content = f.read()
@@ -113,12 +111,6 @@ class YamlLintConfig(object):
             self.yaml_files = pathspec.PathSpec.from_lines('gitwildmatch',
                                                            conf['yaml-files'])
 
-        if 'locale' in conf:
-            if not isinstance(conf['locale'], str):
-                raise YamlLintConfigError(
-                    'invalid config: locale should be a string')
-            self.locale = conf['locale']
-
     def validate(self):
         for id in self.rules:
             try: