Hammer CLI

The api docs for override values has changed in the foreman 1.17 and wrongly document expected types for 'value' and 'default_value' parameters. This results in hammer interpreting the type as a list and passing all the values in arrays.

Unfortunately this happens at multiple places in the api. Since the proper fix includes some tuning on hammer-cli side as well as adding a custom validator to the api and this issue blocks some other PRs that require 1.17 api exports, I propose to do a temporary fix on hammer side. The proper fix can be delivered later.