Reapply the Jacoco version after the project has been evaluated (#128)

* Reapply the Jacoco version after the project has been evaluated, fixes #125

* Initialize the Jacoco version in the root project only once

Author: vRallev

src/main/groovy/com/vanniktech/android/junit/jacoco/GenerationPlugin.groovy

@@ -223,8 +223,11 @@ class GenerationPlugin implements Plugin<Project> {
     private static addJacocoMergeToRootProject(final Project project, final JunitJacocoExtension extension) {
         project.plugins.apply('jacoco')
 
-        project.jacoco {
-            toolVersion extension.jacocoVersion
+        project.afterEvaluate {
+            // Apply the Jacoco version after evaluating the project so that the extension could be configured
+            project.jacoco {
+                toolVersion extension.jacocoVersion
+            }
         }
 
         def mergeTask = project.task("mergeJacocoReports", type: JacocoMerge) {