Integrate AS::Notifications and use it to publish traces.

Adjust debugger example and add logging example.
Create a generic events interface backed by AS::Notifications.

Webmachine::Events implements the AS::Notifications API and uses
AS::Notifications as the default backend. The backend is exchangeable
with any class that implements the AS::Notifications API.
Switch backend from ActiveSupport::Notifications to AS::Notifications.
Merge branch 'master' into as-notifications

Conflicts:
	lib/webmachine/trace/resource_proxy.rb
Add specs for Webmachine::Events.
Add specs for Request#has_body?.
Add LazyRequestBody#empty? method.

This unbreaks Request#has_body? if the body is a LazyRequestBody.
Documentation for Webmachine::Events.
Revert "Add another failing test case for Rack and content-type."

Since the rack adapter uses Rack::Response now, we can revert this.
@pawelpacana confirmed in issue #98 that this is safe.

Unbreaks tests with rack >= 1.5.

This reverts commit f33677849d0c1cad8362a625d17447b87fe56289.
Merge pull request #98 from seancribbs/has_body_fix

Fix Request#has_body? with a LazyRequestBody
Merge pull request #92 from bernd/as-notifications

ActiveSupport::Notifications events framework spike
Add mailing list link.
Add link to webmachine-actionview.
Add description for webmachine-actionview.

[ci skip]
Fix operator precedence in IOEncoder.each.

Causing .each to yield 'true'.
Merge pull request #101 from justinmcp/master

Fix operator precedence in IOEncoder.each.
Merge remote-tracking branch 'upstream/master' into adapter_tests

Conflicts:
	lib/webmachine/streaming/io_encoder.rb
	spec/webmachine/adapters/rack_spec.rb