Add optional automatic response body compression

This behavior can be enabled with the `compress` protocol option.
See the `compress_response` example for more details.

All tests are now ran with and without compression for both HTTP
and HTTPS.

examples/compress_response/src/compress_response_app.erl

@@ -0,0 +1,26 @@
+%% Feel free to use, reuse and abuse the code in this file.
+
+%% @private
+-module(compress_response_app).
+-behaviour(application).
+
+%% API.
+-export([start/2]).
+-export([stop/1]).
+
+%% API.
+
+start(_Type, _Args) ->
+	Dispatch = [
+		{'_', [
+			{[], toppage_handler, []}
+		]}
+	],
+	{ok, _} = cowboy:start_http(http, 100, [{port, 8080}], [
+		{compress, true},
+		{env, [{dispatch, Dispatch}]}
+	]),
+	compress_response_sup:start_link().
+
+stop(_State) ->
+	ok.