Add a config param to force reinstallation of rpms

[mcouthon]

From @mcouthon on September 27, 2017 16:29

This will be useful in the following scenario:

1. A cloudify manager is already installed on the machine.
2. cloudify-bootstrap is reinstalled (possibly bringing a new single tar).

The component RPMs need to be updated in this scenario, but currently if the yum package is installed, we don't install it again.

Copied from original issue: mcouthon/cloudify-manager-install#41

[mcouthon]

Current workaround is to cfy_remove and cfy_install again.