Import exceptions module from openstack-common

Partial implements: blueprint py33-support

Change-Id: Ie24466e8ab5f1c4474e758458ff3c892f1b0dd0d
Replace g.next() with next(g)

In Python 3, g.next() has been renamed to g.__next__().
The next() buildin function will work fine for Python 2&3.

Partial implements: blueprint py33-support
Change-Id: I992d019eb180f514388f21b2400b51c94c7bdad5
Transform print statement to print function

Partial implements: blueprint py33-support

Change-Id: I029cb33b17a98da2ce225abc180f923f94ca0bf6
Replace basestring with six.string_types

six.string_types
  Possible types for text data. This is basestring() in Python 2
  and str in Python 3.

Partial implements: blueprint py33-support

Change-Id: I25b463efdfe2e20af92dd805d4f44b40d4bd4b35
Merge "Import exceptions module from openstack-common"
Merge "Replace g.next() with next(g)"
Merge "Transform print statement to print function"
Merge "Replace basestring with six.string_types"