Fixed Compilation Issue

Unused Imports
Mismatch return parameters.
diff --git a/api/server/server.go b/api/server/server.go
index 71155bd..a46b705 100644
--- a/api/server/server.go
+++ b/api/server/server.go
@@ -19,9 +19,7 @@
 package server
 
 import (
-	"encoding/json"
 	"fmt"
-	"github.com/apache/brooklyn-client/models"
 	"github.com/apache/brooklyn-client/net"
 )
 
@@ -169,7 +167,7 @@
 	if err != nil {
 		return "", nil
 	}
-	return string(body)
+	return string(body), nil
 }
 
 func Export(network *net.Network) (string, error) {
@@ -178,7 +176,7 @@
 	if err != nil {
 		return "", nil
 	}
-	return string(body)
+	return string(body), nil
 }
 
 // WIP
@@ -188,5 +186,5 @@
 	if err != nil {
 		return "", err
 	}
-	return string(body)
+	return string(body), nil
 }