Fix response body of /3pid/bind to match spec

- synapse did not check/validate the response as per spec until 0.99.5 it seems
- mxisd was never compliant also

src/main/java/io/kamax/mxisd/config/MxisdConfig.java

@@ -83,6 +83,12 @@ public class MxisdConfig {
 
     }
 
+    public static MxisdConfig forDomain(String domain) {
+        MxisdConfig cfg = new MxisdConfig();
+        cfg.getMatrix().setDomain(domain);
+        return cfg;
+    }
+
     private AppServiceConfig appsvc = new AppServiceConfig();
     private AuthenticationConfig auth = new AuthenticationConfig();
     private DirectoryConfig directory = new DirectoryConfig();
@@ -309,6 +315,13 @@ public class MxisdConfig {
         this.wordpress = wordpress;
     }
 
+    public MxisdConfig inMemory() {
+        getKey().setPath(":memory:");
+        getStorage().getProvider().getSqlite().setDatabase(":memory:");
+
+        return this;
+    }
+
     public MxisdConfig build() {
         if (StringUtils.isBlank(getServer().getName())) {
             getServer().setName(getMatrix().getDomain());