Make global proxy settings configurable from morpheus.rb

When installing Morpheus if the appliance is behind a proxy, registering or login at Morpheus Hub as first step after reconfigure (to obtain a community license) will not be possible, but a global proxy cannot be set until after master tenant and superuser creation, presenting a catch 22.

Idea, is to make the global proxy settings configurable in morpheus.rb so that the settings can be applied during reconfigure in the same way the appliance url is as well as other advanced settings here

This would enable a license to be obtained in this scenario.