Fix check_networks task result

1. "id" renamed to "ids".
2. "ids" and "errors" are always lists.
3. "range_errors" removed.
4. "errors" values are subsets of NetworkGroup fields names.

Closes-Bug: #1263097

Change-Id: I30bb13c4613cf0b5a3f604ca350b2a594cbdf924
Merge "Fix check_networks task result"