Adding checks for installation prerequisites

Adding checks for installation prerequisites

This patch adds a few preliminary checks for installation prerequisites,
currently covering software dependencies and runtime prerequisites. More
checks need to be added over time.

Signed-off-by: Georg Kunz <georg.kunz@est.tech>
Change-Id: Ic59b99873983511b74ebdce06d3aeb2ade318a76
Reviewed-on: https://gerrit.opnfv.org/gerrit/c/kuberef/+/70841
Tested-by: jenkins-ci <jenkins-opnfv-ci@opnfv.org>
Reviewed-by: Victor Morales <chipahuac@hotmail.com>
Reviewed-by: Rihab Banday <rihab.banday@ericsson.com>