Update translatable strings

Stop using the `_()` function, and use `{% trans %}` tags instead.

calsocial/__init__.py

@@ -86,7 +86,11 @@ class CalendarSocialApp(Flask):
         # Make sure we look up users both by their usernames and email addresses
         self.config['SECURITY_USER_IDENTITY_ATTRIBUTES'] = ('username', 'email')
         self.config['SECURITY_LOGIN_USER_TEMPLATE'] = 'login.html'
+
+        self.jinja_env.policies['ext.i18n.trimmed'] = True  # pylint: disable=no-member
+
         db.init_app(self)
+
         babel = Babel(app=self)
         babel.localeselector(get_locale)