Implement administrative override switch which allows installing even if the safety checks are failing

[brunodam]

Just on a side note, we may want to have an administrative override switch which allows installing even if the safety checks are failing.

This could be a hidden flag or flag with really scary name/description to discourage users from using it without direction from the support team.

We added such a switch to NMT because we ran into edge cases where NMT improperly detected the available system memory.

Originally posted by @nathanklick in #371 (comment)