Handle heat with SQLAlchemy >= 0.8

Lots of unit tests failed with the new SQLAlchemy(0.8.2)
which makes build failed, this patch will fix all the related
bug like no MutableType and changed module name in SQLAlchemy(0.8.2)

Fixes bug #1199435

Change-Id: I67d7588db088dd3dd88d44c32e78c6b8a4708bff
Merge "Handle heat with SQLAlchemy >= 0.8"