Integer(0) will return 0 even 0 is not in the range specified

[Longjie_Cao]

THe line in Integer.__call__ should compare None , not False:
  def __call__(self, value):
        if not isinstance(value, int):
          ....

        if value:
            self._check_range(value)

        return value

Should be modified as:

  def __call__(self, value):
        if not isinstance(value, int):
          ....

        if value is not None:
            self._check_range(value)

        return value

How to reproduce the problem:
>>> from oslo.config import types
>>> Test1 = types.Integer(3,6)
>>> Test1(0)
0

After modification:
>>> from oslo.config import types
>>> Test1 = types.Integer(3,6)
>>> Test1(0)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/usr/lib/python2.7/dist-packages/oslo/config/types.py", line 129, in __call__
    self._check_range(value)
  File "/usr/lib/python2.7/dist-packages/oslo/config/types.py", line 136, in _check_range
    self.min)
ValueError: Should be greater than or equal to 3

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/151940
Committed: https://git.openstack.org/cgit/openstack/oslo.config/commit/?id=0366f880d5222251ce4b6833fa556d11d1e47229
Submitter: Jenkins
Branch: master

commit 0366f880d5222251ce4b6833fa556d11d1e47229
Author: Davanum Srinivas <email address hidden>
Date: Sun Feb 1 15:00:48 2015 -0500

    Better check for integer range to account for 0

    We should be using "if value is not None" to better check
    for the condition where the value is 0 and 0 is not in the
    valid range.

    Co-Authored-By: Longjie_Cao <email address hidden>
    Closes-Bug: #1416212
    Change-Id: Ie5c81f1916e301619955364b040bdc7a9275e29c