Based on #614

WebStorm Karma integration listens to webserver port binding event (i.e. when this line printed https://github.com/karma-runner/karma/blob/v1.0.0-0/lib/server.js#L61).

Now the only way to accomplish this is to parse standard output of Karma server and mine data from lines like:

INFO [karma]: Karma v0.12.37 server started at https://localhost:9876/

Such an approach seems to be not very safe, e.g. it'll fail if logLevel: config.LOG_DISABLE is set. Well, actually, there is a workaround for this case: LOG_DISABLE is not allowed https://github.com/karma-runner/karma-intellij/blob/master/lib/intellij.conf.js#L50. But still it doesn't feel right.

It'd be nice if plugins could use some API to listen to webserver port binding event. Thanks!