merge XD-723: Use smarter Thread.sleep() in tests

Introduce HttpSource and use it in MetricsTests

Don't swallow InterruptedException

Rewrite test using HttpSource and FileSink helper classes
Use same port as before in tests
Fix XD-629: create tap channel for module ending with sink channel
XD-737 - Added cron-trigger and trigger sources

cron-trigger takes 'cron', and trigger takes 'fixedDelay'

10 seconds is the default for both