Issue 4248 - Add codestyle check

libadblockplus-android-settings/build.gradle

 apply plugin: 'com.android.library'
+apply plugin: 'checkstyle'
 
 android {
     compileSdkVersion 21
     buildToolsVersion "25.0.0"
 
     defaultConfig {
         minSdkVersion 21
         targetSdkVersion 21
         versionCode 2
         versionName "1.0.1"
     }
 
     sourceSets {
         main {
             manifest.srcFile 'AndroidManifest.xml'
             java.srcDirs = ['src']
             resources.srcDirs = ['src']
             res.srcDirs = ['res']
             assets.srcDirs = ['assets']
 
             jni {
                 dependencies {
                     project ":libadblockplus-android"
                 }
             }
         }
     }
 }
 
-
-
 dependencies {
     compile project(':libadblockplus-android')
     compile 'com.android.support:support-v4:21.0.3'
+}
+
+checkstyle {
+    toolVersion = '6.19'
+}
+
+task checkstyleMain(type: Checkstyle) {
+    ignoreFailures = true
+    showViolations = true
+    source 'src/org/adblockplus/'
+    exclude '**/gen/**'
+    exclude '**/R.java'
+    exclude '**/BuildConfig.java'
+    reports {
+        xml.destination "$project.buildDir/reports/checkstyle/main.xml"
+    }
+    classpath = files()
+    configFile = file("${rootProject.rootDir}/third_party/checkstyle/java/rules/eyeo_production_checks.xml")
+    configProperties = [
+        "checkstyle.header.file" : file("${rootProject.rootDir}/third_party/checkstyle/java/res/header.txt")
+    ]
 }