slamhound.el doesn't support cider versions 0.8.0+

[lsankar4033]

If you take a look at the changelog, Cider renamed nrepl-send-string-sync to nrepl-sync-request. I believe this just involves a 1 line change here.

I can submit a PR when I get a chance.

[piotrklibert]

I fixed this in #93 and also rewrote the command to be asynchronous.