Expose exception objects via the as keyword
Expose exception objects via the as keyword

According to Python 3 Porting guide
http://docs.pythonsprints.com/python3_porting/py-porting.html

Exceptions were changed in a few ways for Python 3. First, strings
are no longer usable as exceptions. Additionally, the raise syntax no
longer accepts comma-separated arguments, instead working with exception
instances. Perhaps the largest difference in Python 3 is that exception
objects are only available via the as keyword, which was introduced in
2.6.

Change-Id: Ide665ecc4b7f14bd58bafab47e05a86a4cf2d141
Closes-Bug: #1490526

stackforge/kolla,nihilifer/kolla,dardelean/kolla-ansible,mrangana/kolla,mandre/kolla,rahulunair/kolla,coolsvap/kolla,chenzhiwei/kolla,tonyli71/kolla,coolsvap/kolla,intel-onp/kolla,fdumpling/kolla,rajalokan/kolla,openstack/kolla,fdumpling/kolla,limamauricio/mykolla,toby82/kolla,toby82/kolla,stackforge/kolla,openstack/kolla,mandre/kolla,GalenMa/kolla,limamauricio/mykolla,stackforge/kolla,negronjl/kolla,rahulunair/kolla,chenzhiwei/kolla,chenzhiwei/kolla,limamauricio/mykolla,fdumpling/kolla,toby82/kolla,negronjl/kolla,rajalokan/kolla,mrangana/kolla,tonyli71/kolla,nihilifer/kolla,intel-onp/kolla,dardelean/kolla-ansible,coolsvap/kolla,mandre/kolla,negronjl/kolla,GalenMa/kolla,rajalokan/kolla,dardelean/kolla-ansible