Merge the tip of origin/release/proposed/2019.2.0 into origin/release/2019.2.0

99125a7 Add toString() method for package name for isPackageInstalled func
b2a6795 Add common function for getting Salt worker_threads value
4babe45 Update Galera functions for verify/restore
f119aa5 Update runSaltCommand command to support batch
9c56bc0 Get rid of hardcoded node names in pipeline library

Change-Id: Idac9bf2025b0ca7ba194079bf3c433f399f4c516