Fix wrong response structure of router update

For router update operation, only one router is returned instead of a
collection.
Rename routers-get-detail-resp.json to router-get-detail-resp.json (df)

Change-Id: If8e81fad8c2edc2e4752c1f70aaeea8dee62271e
Closes-Bug: #1332547
Merge "Fix wrong response structure of router update"