Make typecasting an extensible hook instead of a hardcoded routine
Make some changes based on working with Gittip
Fix CLI api (was missing entrypoint hook)
Drop back to state as return val

If we store state on Algorithm then we're not thread-safe.
Some reorganization of typecasting due to feedback
fixup release-wheel test in release.sh
Updated Changelog for v0.27
Release 0.27
Bump version to 0.27-dev
Upgrade to dev version of Algorithm
Start dusting off ancient testing doc stub
Fix test suite

I moved the Harness into __init__.py and split it into two: a Harness
base class to be shared with downstream apps, and a _Harness class to be
used in Aspen's own test suite.
Upgrade to standalone version of filesystem_tree
Clean up unicode and cookie in test harness
Merge branch 'master' into issue-240
Fix regression in test_website
Improve test harness

 - catch up with Algorithm API changes
 - fold GET and POST into perform_request; now they're shims
Clean up test_response for lastest Algorithm API
Suppress console spam in testing
Fix regression in test_request.py