Fixing bug in DbMemory.del_list(), where if you passed a filter to delete the whole table it would give index out of bounds. Updated unit test to cover that case.

Change-Id: I1282bd637567ca651ffcd201edfc8ff9fd0950d7
Signed-off-by: Eduardo Sousa <eduardosousa@av.it.pt>
diff --git a/osm_common/dbmemory.py b/osm_common/dbmemory.py
index d7419f4..6f7e4c4 100644
--- a/osm_common/dbmemory.py
+++ b/osm_common/dbmemory.py
@@ -64,7 +64,7 @@
             for i, _ in self._find(table, self._format_filter(filter)):
                 id_list.append(i)
             deleted = len(id_list)
-            for i in id_list:
+            for i in reversed(id_list):
                 del self.db[table][i]
             return {"deleted": deleted}
         except DbException: