Fixed #26808 -- Added Meta.indexes for class-based indexes.

* Added the index name to its deconstruction.
* Added indexes to sqlite3.schema._remake_table() so that indexes
  aren't dropped when _remake_table() is called.

Thanks timgraham & MarkusH for review and advice.

django/db/models/options.py

@@ -99,6 +99,7 @@ class Options(object):
         self.db_table = ''
         self.ordering = []
         self._ordering_clash = False
+        self.indexes = []
         self.unique_together = []
         self.index_together = []
         self.select_on_save = False