Allow project configs to be saved as default

[justinquinnb]

After a project has been initialized with a non-previously-existing configuration, prompt the user to save and name the config for later re-use.

Configs saved globally for reuse can then be set as a default for projects that haven't been configured yet (auto init from existing config).

If auto init from existing config is disabled, prompt the user to pull from the list of existing global config files upon project initialization.