Use fast option to minimize simulated latency with fakeredis

Wow, great find with fakeredis. Much better API coverage than what I had been using. It's neat that it offers simulated latency as well, though it seems to be a bit much. Considering your lib doesn't have any setTimeouts and the asynchronous flow is easy to follow, you could probably disable it. Otherwise the specs might become a bit slow to run as you add features.

Before:

```
$ jasmine-node spec
.............

Finished in 2.152 seconds
13 tests, 33 assertions, 0 failures, 0 skipped
```

After

```
$ jasmine-node spec
.............

Finished in 0.369 seconds
13 tests, 33 assertions, 0 failures, 0 skipped
```