Unable to start chronograf via docker-compose

Hi

I have just cloned the repo and run the `./sandbox up` script.

But in looking at Chronograf, I see the following:

`time="2018-03-23T17:33:06Z" level=error msg="Unable to open boltdb; is there a chronograf already running? invalid argument" component=boltstore`

I'm running Docker version `18.01.0-ce, build 03596f5` on Mac OS X 10.12.6

Kapacitor also gives and error, which is likely related:

`ts=2018-03-23T17:33:06.239Z lvl=error msg="encountered error" service=run err="open server: open service *storage.Service: open boltdb @ \"/var/lib/kapacitor/kapacitor.db\": invalid argument"
run: open server: open service *storage.Service: open boltdb @ "/var/lib/kapacitor/kapacitor.db": invalid argument`