Move module level funcs to unit tests that use 'em

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: I947dfceff01499ca09f3887157dc3bbcbcc0f20b
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.

Change-Id: I50b9fb798fbfd1d552b3c3f90309f6b86da34853