Allows to skip client build when doing make prog/scope (#2732)
Allows to skip client build when doing make prog/scope (#2732)

When you run the client locally with `yarn start` and modify the
app/probe code you don't want to compile the client on `make prog/scope`.

This allows you to do `SCOPE_SKIP_UI_ASSETS=true make prog/scope` to
only build the scope binary.
alban/scope,alban/scope,alban/scope,kinvolk/scope,kinvolk/scope,alban/scope,weaveworks/scope,weaveworks/scope,weaveworks/scope,weaveworks/scope,kinvolk/scope,kinvolk/scope,kinvolk/scope,alban/scope,kinvolk/scope,weaveworks/scope,weaveworks/scope,alban/scope