Push support
Changed push support to a pimp and middleware pair
Examples of push support.
Removed a wrapping Future. Renamed some vals.
Made push a bit safer.
Legacy x-compress and x-gzip content codings.
Transfer-Encoding takes transfer-coding values.
Merge branch 'topic/push' into develop
Add a case-insensitive String.

We're going to be doing this a lot, and the tagged type is usually
going to be paired with the original value.  We might as well bundle
it as a type.

scalaz.CaseInsensitive falls short beacuse it uses the default locale.
This fails The Turkey Test unless we're more careful about the implicit
FoldCase than I expect we'll be.
Merge branch 'develop' into topic/scalaz-task

Conflicts:
	core/src/main/scala/org/http4s/MockServer.scala
	core/src/main/scala/org/http4s/Response.scala
	core/src/main/scala/org/http4s/package.scala
	core/src/test/scala/org/http4s/ExampleRoute.scala
	core/src/test/scala/org/http4s/MockServerSpec.scala
	netty/src/main/scala/org/http4s/netty/Http4sNetty.scala
	servlet/src/main/scala/org/http4s/servlet/Http4sServlet.scala