add basic_auth test

Signed-off-by: Mohammed Al Sahaf <msaa1990@gmail.com>

caddytest/spec/http/basicauth/spec.hurl

@@ -0,0 +1,38 @@
+# Configure Caddy
+POST http://localhost:2019/load
+Content-Type: text/caddyfile
+```
+{
+	skip_install_trust
+	http_port     9080
+	https_port    9443
+	local_certs
+	debug
+}
+localhost {
+	log
+	basic_auth {
+		john $2a$14$x4HlYwA9Zeer4RkMEYbUzug9XxWmncneR.dcMs.UjalR95URnHg5.
+	}
+	respond "Hello, World!"
+}
+```
+
+# requests without `Authorization` header are rejected with 401
+GET https://localhost:9443
+[Options]
+insecure: true
+HTTP 401
+[Asserts]
+header "WWW-Authenticate" == "Basic realm=\"restricted\""
+
+
+# requests with `Authorization` header are accepted with 200
+GET https://localhost:9443
+[BasicAuth]
+john:password
+[Options]
+insecure: true
+HTTP 200
+[Asserts]
+`Hello, World!`