factor out the Asynchronizer threading boiler plate
add a Serializer work scheduler
pep8
minor spelling corrections
docstring corrections
reduce wait time
correct test name
remove dublicate line
Merge pull request #52 from enthought/add-serializer

Add serializer
Merge ThreadPoolExecutor changes from Python 3.x that fix polling workers.
Merge pull request #53 from enthought/fix-workers-dont-poll

Merge ThreadPoolExecutor changes from Python 3.x that fix polling workers.
use DynamicURLStore.parts consistently
dynamic_url_store test
Merge pull request #54 from mgummelt/parts

use DynamicURLStore.parts consistently