Don't run long test suites by default

The examples test suite is only useful once in a while
in order to know whether examples were broken, for example
before issuing a release.

The new ws_autobahn test suite isolates the autobahn test
suite so that it can be ignored by default. It's only
useful to run it when working on the Websocket code or
before issuing a release.

test/ws_autobahn_SUITE_data/client.json

@@ -0,0 +1,14 @@
+{
+	"options": {"failByDrop": false},
+	"enable-ssl": false,
+
+	"servers": [{
+		"agent": "Cowboy",
+		"url": "ws://localhost:33080/ws_echo",
+		"options": {"version": 18}
+	}],
+
+	"cases": ["*"],
+	"exclude-cases": [],
+	"exclude-agent-cases": {}
+}