As articulated in #714, the way config defaults to workspace-local
configuration is a bit error prone, especially now with the cloud
workflow being the default. This change implements several improvements:
* First, --save defaults to true, so that configuration changes will
persist into your project file. If you want the old local workspace
behavior, you can specify --save=false.
* Second, the order in which we applied configuration was a little
strange, because workspace settings overwrote project settings.
The order is changed now so that we take most specific over least
specific configuration. Per-stack is considered more specific
than global and project settings are considered more specific
than workspace.
* We now warn anytime workspace local configuration is used. This
is a developer scenario and can have subtle effects. It is simply
not safe to use in a team environment. In fact, I lost an arm
this morning due to workspace config... and that's why you always
issue warnings for unsafe things.