Deprecate bonnie++, aerospike, and redis benchmarks

I propose we deprecate the following benchmarks for release 1.5, and remove them for release 1.6.

| if you use ... | suggested replacement |
| --- | --- |
| `bonnie++` | `fio` |
| `aerospike` | `aerospike_ycsb` |
| `redis` | `redis_ycsb` |

I deliberately did not include `cassandra_stress` in this list, because while we do have `cassandra_ycsb`, both benchmarks are still in use.

If you have any objections to deprecating these benchmarks, please comment on this issue.