It is now possible to deploy either 1.x or 2.x version of Prometheus.
The new 2.x version introduces breaking changes in terms of storage
format and command line options.

Change-Id: I80cc6f1947f3740ef04b29839bfa655b14fae146
Co-Authored-By: Radosław Piliszek <radoslaw.piliszek@gmail.com>