Bug: 1025929
(based on the patch submitted by Ivan Bondarev)
* keystoneclient/v2_0/shell.py
do_tenant_update(): Update description if it is defined.
* keystoneclient/v2_0/tenants.py
Token.update(), TokenManager.update():
Update description if it is defined, even if it's empty.
* tests/v2_0/test_tenants.py
test_update_empty_description(): New test case for empty
description.
Change-Id: I4c4e93f6bd5d38828685fd55eb1e694f521928e9