Make proxy implicit parameter
Add convenience method Request.accept(ContentType)
Add convenience methods to get header and content type from Response
Add convenience methods to get header and content type from Response
contentType convenience method return a ContentType instead of a String
Call connection.disconnect b4 returning response to caller, as this makes subsequent calls much faster (by a factor of about 10, e.g. in tests from 1000+ millis to about 13 millis)
HTTPS support
Adapt HTTPS to the new API

where the configuration is passed into https factory method via implicits
Merge remote-tracking branch 'remotes/origin/https' into https

Conflicts:
	src/main/scala/io/shaka/http/ClientHttpsHandler.scala
	src/main/scala/io/shaka/http/Http.scala
	src/test/scala/io/shaka/http/HttpsSpec.scala