--restart-tries interaction with --kill-others

Hey there!

I'm trying to use concurrently on our CI server to run our integration tests. I'm running into a similar issue as that documented in #177, the difference being I'm also using restartTries to help ensure the server is up before the integration tests run. With this setup, the tests pass, successfully killing the server process, but it restarts the server because of restartTries.

concurrently --kill-others --success first --restart-tries 2 --restart-after 5000 "npm start" "npm test"

...

[1] npm test exited with code 0
--> Sending SIGTERM to other processes..
[0] 2018-12-14T03:31:02.097Z - warn:    Caught SIGTERM, exiting
[0] npm start exited with code SIGTERM
[0] npm start restarted

Any suggestions around this? I'm not sure if this is a supported use case, otherwise it seems like I'll need to modify our tests themselves to ensure the server is up and running

Start by reproducing the command shown in the issue: concurrently --kill-others --success first --restart-tries 2 --restart-after 5000 "npm start" "npm test". Read the restart and kill-others behavior around the process that receives SIGTERM, using issue #177 for context. Done means the successful test process can stop the server without triggering an unwanted restart.