Build upon default detekt config (#2227)
Build upon default detekt config (#2227)

Fixes #2217

When a new rule is added before it's available in the version of detekt that the Gradle plugin uses, the config validation fails because the default detekt config file includes a config for the new rule that the Gradle plugin's detekt version doesn't yet know about.
arturbosch/detekt,rock3r/detekt,arturbosch/detekt,rock3r/detekt,arturbosch/detekt,rock3r/detekt