Slack link in readme is dead

[felixwatts]

Getting https://slack.openfarm.cc gives me ERR_SSL_PROTOCOL_ERROR

[aaferrari]

I take advantage of this issue to comment that when trying to access the assets in https://drive.google.com/open?id=0B-wExYzQcnp3cGphOGZQS1lBRFk the page says that you have to request access to the owner of the file (although I have no idea if this was always the case or if it is a recent change in Google Drive).