Sleep for slack

[kmarekspartz]

This addresses the following:

In general we allow applications that integrate with Slack to send no more than one message per second.

From: https://api.slack.com/docs/rate-limits

Thanks, @katherinelim!

This does not fix #132 completely, as we're still making more requests than necessary, but should mean we do not have to do the rate limit sleeps.

[coveralls]

Coverage decreased (-0.2%) to 70.53% when pulling 76d4981 on kmarekspartz:sleep-1-before-requests-to-slack into d8281fa on randsleadershipslack:master.

[coveralls]

Coverage decreased (-0.2%) to 70.53% when pulling 386118a on kmarekspartz:sleep-1-before-requests-to-slack into d8281fa on randsleadershipslack:master.

[kmarekspartz]

Unfortunately, when I tested this, it took almost twice as long. I'm thinking about putting this behind an environment flag for now, so that @katherinelim can enable it, then doing #132, then turn this on by default.

[ChipWolf]

We've pulled this into our version in order to ensure compliance with Slack's ToS, excluding line 63 which isn't necessary and should resolve @kmarekspartz's speed concern

[kmarekspartz]

Closing as stale