Honor user's browser language (#558)

Previously we would attempt to satisfy the user's first language
preference, immediately falling back to english if that was not
possible. Now, we will get the best match of the user's preferred
languages.

This requires storing the available locales on app startup, so we
have mg_globals.available_locales ready to compare them against the
list of preferred user languages.

Signed-off-by: Sebastian Spaeth <Sebastian@SSpaeth.de>

mediagoblin/init/__init__.py

@@ -19,6 +19,7 @@ from beaker.util import parse_cache_config_options
 import jinja2
 
 from mediagoblin.tools import staticdirect
+from mediagoblin.tools.translate import get_available_locales
 from mediagoblin.init.config import (
     read_mediagoblin_config, generate_validation_report)
 from mediagoblin import mg_globals
@@ -37,6 +38,11 @@ class ImproperlyConfigured(Error):
     pass
 
 
+def setup_locales():
+    """Checks which language translations are available and sets them"""
+    setup_globals(available_locales=get_available_locales())
+
+
 def setup_global_and_app_config(config_path):
     global_config, validation_result = read_mediagoblin_config(config_path)
     app_config = global_config['mediagoblin']