Added IDH plugin to savanna config

Implements blueprint idh-savanna-plugin

Change-Id: Ida02be6bb627d43e196106edf239522240c7eadf
[IDH] Removed copy-pasted test utility file

It seems that code was copied to IDH plugin before extracting test
utils from vanilla plugin to common code. Replaced copy-past with
usage of common code.

Change-Id: I452cc7f274a54f6e5e4972556d2cfc129069871e
Merge "Added IDH plugin to savanna config"
Merge "[IDH] Removed copy-pasted test utility file"