Decouple the config dependence on glance domain

Move the configurations which core domain objects depend on to
common/config.py, and add a argument "task_time_to_live" of Task's
 __init__ method and TaskFactory's new_task method for delivering
the CONF.task.task_time_to_live value.
For convenience,the argument "task_time_to_live" is set a default value 48.

Change-Id: Iffda1ecd25470824c812d66a27fa64ebbaabcf07
Closes-Bug: #1250633