upgrade gradle and build tools

app/build.gradle

@@ -22,6 +22,7 @@ android {
         versionCode 49
         versionName "3.1"
         testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
+        vectorDrawables.useSupportLibrary = true
     }
     buildTypes {
         release {

build.gradle

@@ -7,7 +7,7 @@ buildscript {
         google()
     }
     dependencies {
-        classpath 'com.android.tools.build:gradle:3.1.4'
+        classpath 'com.android.tools.build:gradle:3.2.0'
         classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlin_version"
     }
 }

gradle/wrapper/gradle-wrapper.properties

@@ -1,6 +1,6 @@
-#Thu Aug 28 15:18:36 CEST 2018
+#Tue Sep 25 18:42:11 CEST 2018
 distributionBase=GRADLE_USER_HOME
 distributionPath=wrapper/dists
 zipStoreBase=GRADLE_USER_HOME
 zipStorePath=wrapper/dists
-distributionUrl=https\://services.gradle.org/distributions/gradle-4.4-all.zip
+distributionUrl=https\://services.gradle.org/distributions/gradle-4.6-all.zip