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"
Add importable SwiftService incorporating shell.py logic

This patch adds a SwiftService class that incorporates the high
level logic from swiftclient/shell.py. It also ports shell.py to
use the new class, and updates the code in swiftclient/multithreading.py
to allow the SwiftService to be used for multiple operations whilst
using only one thread pool.

Change-Id: I08c5796b4c01001d79fd571651c3017c16462ffd
Implements: blueprint bin-swift-logic-as-importable-library