1) Replace the deprecated unit test method.
2) Wraps filter usage in a list call.
3) Converts the old metaclass syntax to new.
4) Use range instead of xrange method.
5) Change Unicode to str.
6) Several other transformations.
7) Fixed change password test cases.
8) Use simplejson instead of plain JSON.
Fixed an issue where schema diff showing changes in the identical domain constraints. Fixes#5315
Ignore the keys from the source and target list and also sort both the lists.
Currently supported objects are Table, View, Materialized View, Function and Procedure.
Backend comparison of two schemas implemented by: Akshay Joshi
Fixes#3452.