Use eventlet instead of threading for timeout

The only explicit use of Python threading is found in the
testFileSizeLimit test. Using eventlet seems a bit easier to follow,
accomplishing the same goal, and does not constrain us to a
multi-threaded environment.

The chunks() and timeout() module level functions are only used by one
test each, so we just move them to those tests to indicate they are not
used globally.

Change-Id: I50b9fb798fbfd1d552b3c3f90309f6b86da34853
Fix logging issue when services stop on py26

On older versions of python 2.6, exceptions would be spewed to the error
log whenever a service would stop.  This gets magnified by the
container-updater which seems to do it with every pass.  This catches
and squelches the error.

Change-Id: I128c09c240e768e8195af1f6fe79b10d4e432471
Closes-Bug: #1306027
Merge "Use eventlet instead of threading for timeout"
Merge "Fix logging issue when services stop on py26"
Load constraints from cluster info dictionary

Rather than using the constraints module, and detecting if
/etc/swift/swift.conf was loaded, etc. we just use the cluster_info for
the constraints now that they are always present.

Change-Id: Iea01c9c4b5148faa10004a240df411cbe7336a6a