If browser not installed in expected location, karma will hang and time out

[blackbaud-brandonhare]

If the browser used to launch karma is not installed in the expected location, karma will attempt to launch it and then time out. No error is logged. To duplicate on Mac:

1. Delete chrome from the Applications directory.
2. Run skyux test or skyux watch.
3. The runner will attempt to launch the browser, but won't find it and hang.

I was able to figure this out by troubleshooting based on this comment: karma-runner/karma#1206 (comment)

It would be nice if it threw an error somehow to indicate what the issue is.

[Blackbaud-SteveBrush]

When using Chrome launcher, the output from Karma is currently (for more context):

10 04 2019 12:05:06.633:WARN [launcher]: Chrome have not captured in 300000 ms, killing.
10 04 2019 12:05:08.640:WARN [launcher]: Chrome was not killed in 2000 ms, sending SIGKILL.
10 04 2019 12:05:10.644:WARN [launcher]: Chrome was not killed by SIGKILL in 2000 ms, continuing.

[Blackbaud-AlexKingman]

Closing due to inactivity.