Replace scalalogging with log4s. #65
slf4s was something else, this is log4s.
Merge branch 'develop' into topic/log4s

Conflicts:
	servlet/src/main/scala/org/http4s/servlet/Http4sServlet.scala
Bump to log4s-1.1.2.
Merge pull request #66 from http4s/topic/log4s

Replace scalalogging with log4s. #65