Groovy let me shoot myself in the foot by allowing a string in
a boolean condition... and "false" evaluates to true. Argh.

Setting enabled=false still loads clover and expects a license,
it just doesn't instrument.

Define includeTasks so we don't include any real tasks as a
work-around for this.

Not entirely sure how to enable it again at runtime though :)

`./gradlew clean cloverAggregateReport` in meta will create a new
report for all the projects with tests.

Plugins that don't have any tests won't show up at all.