Reordering of fields on schema is not preserved

## Gentics Mesh Version, operating system, or hardware.
- v1.3.2

## Operating System
- Linux

## JVM
- Oracle JDK 1.8.0_100
## Problem
Create an schema add multiple fields to it. (save)
Re-edit the schema, reorder the fields using the UI drag bars. (save)
Re-enter the schema: the fields are out of order.
Try to create a node using the schema: the fields are not in order.
## Reproducer
Try reordering the following schema:
{
"name": "b2g_app_config",
"container": true,
"autoPurge": false,
"description": "Main node configuring a white-label",
"displayField": "title",
"segmentField": null,
"urlFields": [
"id"
],
"fields": [
{
"name": "home_upcoming",
"type": "list",
"label": "Home Upcoming",
"required": true,
"listType": "micronode"
},
{
"name": "id",
"type": "string",
"label": "URL Slug",
"required": true
},
{
"name": "league_upcoming",
"type": "list",
"label": "League Upcoming",
"required": true,
"listType": "micronode"
},
{
"name": "menu_pages",
"type": "list",
"label": "Additional Pages",
"required": false,
"listType": "micronode"
},
{
"name": "pages_upcoming",
"type": "list",
"label": "Pages Upcoming",
"required": false,
"listType": "micronode"
},
{
"name": "sport_upcoming",
"type": "list",
"label": "Sport Upcoming",
"required": true,
"listType": "micronode"
},
{
"name": "title",
"type": "string",
"label": "Title",
"required": true
},
{
"name": "top_sports",
"type": "list",
"label": "Top Sports",
"required": true,
"listType": "micronode"
}
]
}
## Expected behaviour and actual behaviour
The reordering is preserved.
Actual behaviour: the reordering is not preserved.