add kotlin

app/build.gradle

@@ -24,6 +24,10 @@ android {
             signingConfig signingConfigs.release
         }
     }
+
+    sourceSets {
+        main.java.srcDirs += 'src/main/kotlin'
+    }
 }
 
 dependencies {
@@ -33,10 +37,23 @@ dependencies {
     compile 'com.jakewharton:butterknife:8.0.1'
     compile 'com.simplemobiletools:filepicker:1.3.3@aar'
     compile 'com.github.bumptech.glide:glide:3.7.0'
+    compile "org.jetbrains.kotlin:kotlin-stdlib:$kotlin_version"
 
     apt 'com.jakewharton:butterknife-compiler:8.0.1'
 }
 
+buildscript {
+    ext.kotlin_version = '1.0.3'
+    repositories {
+        mavenCentral()
+    }
+
+    dependencies {
+        classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlin_version"
+        classpath "org.jetbrains.kotlin:kotlin-android-extensions:$kotlin_version"
+    }
+}
+
 def Properties props = new Properties()
 def propFile = new File('signing.properties')
 if (propFile.canRead()) {