Crypto lesson (#712)

* crypto lesson added

* signing assignment

* integration test added for signing assignment

* added more hints

* corrections after rebase

* added some explanation

* added security defaults assignment

webgoat-lessons/pom.xml

@@ -39,6 +39,7 @@
         <module>ssrf</module>
         <module>secure-passwords</module>
         <module>webgoat-lesson-template</module>
+		<module>crypto</module>
     </modules>
 
     <dependencies>