build: avoid multiple refreshes when running unit tests locally

[crisbeto]

Avoids Karma running tests multiple times when developing locally, due to it triggering a test run whenever a new file is written to disk. This change switches to manually spawning a Karma server and then running the tests by depending on Gulp's API instead.

For reference, here's what running tests on master looks like:

And here's what it looks like with the new changes:

[jelbourn]

LGTM

I tried it out, way way better. Thanks!

[jelbourn]

@crisbeto can you rebase?

[crisbeto]

Done @jelbourn.

[angular-automatic-lock-bot]

This issue has been automatically locked due to inactivity.
Please file a new issue if you are encountering a similar or related problem.

Read more about our automatic conversation locking policy.

_{This action has been performed automatically by a bot.}