potential for black-holing log messages via transitive dependency on gulplog

`gulp-util.log` checks for `hasGulplog` on module initialization and if present, defers logging to `gulplog.info`, which in turn will eat any messages below `error` (I believe) unless there is explicitly an event handler for the other levels (info, warn, etc.).

This can happen 'accidentally' if a transitive dependency uses gulplog.

It _seems_ like the reasonable thing to do is to use `gulplog.error` to ensure all logging is output properly.

Start by tracing gulp-util.log's module initialization and its hasGulplog path into gulplog.info. Reproduce the case where a transitive dependency loads gulplog and lower-severity messages disappear, then verify that the chosen logging behavior preserves output for those messages.

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