correct DBHOST substitution in config.json

frameworks/Groovy/hot/config.json

@@ -5,7 +5,7 @@
   "dataSources" : [ {
     "name" : "mongo",
     "engine" : "MONGODB",
-    "hostname" : "$DBHOST",
+    "hostname" : "localhost",
     "port" : 27017,
     "database" : "hello_world",
     "username" : "",

frameworks/Groovy/hot/setup.sh

@@ -1,5 +1,7 @@
 #!/bin/bash
 
+sed -i 's|localhost|'"${DBHOST}"'|g' config.json
+
 fw_depends java hot
 
 ${HOT_HOME}/hot run