Merge branch 'checkstyle-6.18' into 'master'

checkstyle: bump to 6.18

Also, forgot to simplify the checkstyle setup in the extension after we
moved from an ant folder hierarchy to a gradle one. Do that now.

See merge request !272

Privileged-Extension/build.gradle

@@ -36,14 +36,13 @@ android {
 }
 
 checkstyle {
-    toolVersion = '6.17'
+    toolVersion = '6.18'
 }
 
 task checkstyle(type: Checkstyle) {
     configFile file("${project.rootDir}/config/checkstyle/checkstyle.xml")
-    source 'src'
+    source 'src/main/java'
     include '**/*.java'
-    exclude '**/gen/**'
 
     classpath = files()
 }

app/build.gradle

@@ -191,7 +191,7 @@ android {
 }
 
 checkstyle {
-    toolVersion = '6.17'
+    toolVersion = '6.18'
 }
 
 task checkstyle(type: Checkstyle) {