Updated Android Gradle Build plugin

Also added the wrapper config to avoid old versions of Gradle messing up

build.gradle

@@ -7,7 +7,7 @@ buildscript {
         jcenter()
     }
     dependencies {
-        classpath 'com.android.tools.build:gradle:3.0.1'
+        classpath 'com.android.tools.build:gradle:3.1.0'
         classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlin_version"
         classpath "org.junit.platform:junit-platform-gradle-plugin:+"
 
@@ -51,4 +51,4 @@ subprojects.findAll { it.name.equalsIgnoreCase("common") or it.name.equalsIgnore
 
 task clean(type: Delete) {
     delete rootProject.buildDir
-}
+}

gradle/wrapper/gradle-wrapper.properties

@@ -0,0 +1,5 @@
+distributionBase=GRADLE_USER_HOME
+distributionPath=wrapper/dists
+distributionUrl=https\://services.gradle.org/distributions/gradle-4.6-bin.zip
+zipStoreBase=GRADLE_USER_HOME
+zipStorePath=wrapper/dists