Fix crypto

A recent change in synapse shown that the various classes handling crypto were broken.
All the crypto code has been refactored in the SDK and the local code has been adapted.

src/main/java/io/kamax/mxisd/lookup/SingleLookupReply.java

@@ -33,7 +33,6 @@ public class SingleLookupReply {
     private static Gson gson = new Gson();
 
     private boolean isRecursive;
-    private boolean isSigned;
     private String body;
     private SingleLookupRequest request;
     private _MatrixID mxid;
@@ -53,7 +52,6 @@ public class SingleLookupReply {
             reply.notAfter = Instant.ofEpochMilli(json.getNot_after());
             reply.notBefore = Instant.ofEpochMilli(json.getNot_before());
             reply.timestamp = Instant.ofEpochMilli(json.getTs());
-            reply.isSigned = json.isSigned();
         } catch (JsonSyntaxException e) {
             // stub - we only want to try, nothing more
         }
@@ -85,10 +83,6 @@ public class SingleLookupReply {
         return isRecursive;
     }
 
-    public boolean isSigned() {
-        return isSigned;
-    }
-
     public String getBody() {
         return body;
     }