There are a lot of places where _make_foo_list()s are implemented.
Actually base.obj_make_list() can be used to make the list.
The patch is to clean up the redundancies and make the code clean.
Also, in order to make _from_db_objects()s the same format, we add
'context' into the parameter list in instance fault object.
Related to blueprint icehouse-objects.
Change-Id: I1a68b6e9dc402d4e30a06f94b068233e2afa713f