Upgrade to gradle 4.4.1

build.gradle

@@ -3,14 +3,15 @@ apply plugin: 'com.github.ben-manes.versions'
 buildscript {
     repositories {
         jcenter()
+        google()
     }
 
     dependencies {
         // NOTE: Always use fixed version codes not dynamic ones, e.g. 0.7.3 instead of 0.7.+, see README for more information
-        classpath 'com.android.tools.build:gradle:2.2.3'
+        classpath 'com.android.tools.build:gradle:3.0.1'
         classpath files('gradle-witness.jar')
         // bintray dependency to satisfy dependency of openpgp-api lib
-        classpath 'com.novoda:bintray-release:0.2.7'
+        classpath 'com.novoda:bintray-release:0.8.0'
 
         classpath 'org.kt3k.gradle.plugin:coveralls-gradle-plugin:2.6.3'
 
@@ -24,6 +25,7 @@ buildscript {
 allprojects {
     repositories {
         jcenter()
+        google()
     }
 }
 
@@ -50,5 +52,4 @@ project(':extern:bouncycastle') {
 // See http://tools.android.com/tech-docs/new-build-system/tips#TOC-Controlling-Android-properties-of-all-your-modules-from-the-main-project.
 ext {
     compileSdkVersion = 25
-    buildToolsVersion = '25.0.2'
 }