title: Detekt task fails only if ran without check task
body: <p>I'm migrating detekt from 1.0.0.RC7-2 to the 1.0.1 and changing to use the new plugin syntax. I managed to make it work, but only when the full check task is executed.</p>
  
  <p>If only the detekt task is executed then an error is shown.</p>
  
  <p><strong>The detekt task is failing with the following error:</strong></p>
  
  <pre><code>Task :detekt FAILED
  
  FAILURE: Build failed with an exception.
  
  * What went wrong:
  Execution failed for task ':detekt'.
  Could not resolve all files for configuration ':detekt'.
  Cannot resolve external dependency io.gitlab.arturbosch.detekt:detekt-cli:1.0.1 because no repositories are defined.
  Required by:
       project :
  </code></pre>
  
  <p><strong>detekt.gradle</strong></p>
  
  <pre><code>apply plugin: 'io.gitlab.arturbosch.detekt'
  
  detekt {
      config = files("$rootDir/detekt/detekt-ruleset.yml")
      filters = ".*build.*,.*/resources/.*,.*/tmp/.*"
      input = files("src/main/java", "src/test/java")
      reports {
          html.enabled = true
          xml.enabled = false
          txt.enabled = false
      }
  }
  </code></pre>
  
  <p><strong>build.gradle</strong> (project):</p>
  
  <pre><code>buildscript {
      ext.kotlin_version = '1.3.50'
      repositories {
          jcenter()
          google()
      }
  
      dependencies {
          classpath 'com.android.tools.build:gradle:3.4.2'
          classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlin_version"
          classpath "io.gitlab.arturbosch.detekt:detekt-gradle-plugin:1.0.1"
      }
  }
  
  plugins {
       id "io.gitlab.arturbosch.detekt" version "1.0.1"
  }
  </code></pre>
  
  <p><strong>build.gradle</strong> (module):</p>
  
  <pre><code>repositories {
      jcenter()
      google()
  }
  
  apply from: "$rootDir/detekt/detekt.gradle"
  </code></pre>