[DISCUSS] Add neo4j-gremlin-bolt to provider index

[Stephen Mallette]

It looks like neo4j-gremlin-bolt meets our policy for adding it to our
provider index. I asked the maintainer if he'd like it added and the answer
was "yes". Unless there are objections in the next 72 hours (Sunday,
October 23, 2016 at 10am EST), I will assume lazy consensus and add it to
the index.