server: link attribute updates

Tested for name changes only, with the next commit's client side change.

Notes:

uses more than a single query to change each link's name. Since we use
label's, and neo4j is finniky about them, we must:
1. create a new link with copied properties (for future proofing, we use
none at the moment)
2. delete the old link.

Cannot do those in the same statement, the following results in a Neo4j
error:

match a-[l]->b create a-[l2:Poo]->b set l2=l delete l

"errors": [
     {
         "code": "Neo.DatabaseError.Statement.ExecutionFailure",
         "message": "Relationship 13 has been deleted",
         "stackTrace": <snip>
     }
]

0 files changed, 0 insertions, 0 deletions