Clean up namespace by moving extractor DSL to own package.
Few performance overides on HeaderCollection and made it a Value Class

Removed some commented code.
imported the postfix ops bs to get rid of the compiler error.
content-coding cleanup
Case insensitive string cleanup. Now safe across default locales.
Unify registries.
Merge branch 'topic/dsl' into develop

Conflicts:
	core/src/main/scala/org/http4s/Method.scala
	core/src/main/scala/org/http4s/package.scala
	core/src/test/scala/org/http4s/dsl/PathSpec.scala
Spin off DSL module.
Merge branch 'develop' into topic/scalaz-task

Conflicts:
	core/src/main/scala/org/http4s/Method.scala
	core/src/main/scala/org/http4s/package.scala
	core/src/test/scala/org/http4s/ExampleRoute.scala
	examples/src/main/scala/org/http4s/examples/ExampleRoute.scala
	netty/src/main/scala/org/http4s/netty/Http4sNetty.scala
	servlet/src/main/scala/org/http4s/servlet/Http4sServlet.scala