Adding Swift Temporary URL support

Temporary URLs allow a user to sign an object URL with a shared
secret to so that the object can be downloaded without auth for
a specified amount of time.

http://docs.openstack.org/trunk/config-reference/content/object-storage-tempurl.html

Change-Id: Ife0b6c98c975e074d4dad0a31145573b784747c5
Merge "Adding Swift Temporary URL support"