Unescaping any json body entries

without this change we're escaping the json body response and then wiremock is escaping it again
with this change we're unescaping the first json body escaping so that wiremock applies it only once

fixes gh-515

samples/standalone/contracts/com/example/server/pom.xml

@@ -13,7 +13,7 @@
 	<parent>
 		<groupId>org.springframework.boot</groupId>
 		<artifactId>spring-boot-starter-parent</artifactId>
-		<version>1.5.8.RELEASE</version>
+		<version>1.5.9.RELEASE</version>
 		<relativePath />
 	</parent>