Move settings validation from module import to program start

mopidy/__init__.py

@@ -28,4 +28,3 @@ class SettingsError(MopidyException):
 from mopidy import settings as default_settings_module
 from mopidy.utils.settings import SettingsProxy
 settings = SettingsProxy(default_settings_module)
-settings.validate()

mopidy/__main__.py

@@ -19,6 +19,7 @@ logger = logging.getLogger('mopidy.main')
 def main():
     options = _parse_options()
     _setup_logging(options.verbosity_level, options.dump)
+    settings.validate()
     logger.info('-- Starting Mopidy --')
     get_or_create_folder('~/.mopidy/')
     core_queue = multiprocessing.Queue()