Bumps version to 0.23a1.
PhantomJSController: Uses consistent page scrolling. Lengthen page size.
proxy.py: Ignores StreamClosedError from clients using proxy.
connection.py: Fixes handling of HTTP 204.
processor.py: Fixes url_item not processed when robots.txt denies a URL.
changelog: Updates latest to 0.22.1.
Bumps version to 0.22.1

Merge branch 'develop'

Conflicts:
	wpull/version.py