Fix testdpc target25 build flavor can't be installed in pre-O devices

I can reprdouce issue #31, that is even target25 buid flavor can't be
installed in pre-O device.

And for some reason, updating gradle plugin to 3.0.0-alpha1 fixed the
issue. And this also required using default toolchain rather jack.

This closes #31.

Author: ming030890

app/build.gradle

@@ -20,9 +20,6 @@ android {
         targetSdkVersion 26
         versionCode versionMajor * 1000 + versionMinor * 100 + versionBuild
         versionName "${versionMajor}.${versionMinor}.${versionBuild}"
-        jackOptions {
-          enabled true
-        }
     }
 
     buildTypes {
@@ -32,6 +29,7 @@ android {
         }
     }
 
+    flavorDimensions "api"
     productFlavors {
         target25 {
             targetSdkVersion 25
@@ -59,6 +57,9 @@ android {
         flatDir {
             dirs 'libs'
         }
+        maven {
+            url 'https://maven.google.com'
+        }
     }
 }
 

build.gradle

@@ -5,7 +5,7 @@ buildscript {
         jcenter()
     }
     dependencies {
-        classpath 'com.android.tools.build:gradle:2.2.0'
+        classpath 'com.android.tools.build:gradle:3.0.0-alpha1'
 
         // NOTE: Do not place your application dependencies here; they belong
         // in the individual module build.gradle files

gradle/wrapper/gradle-wrapper.properties

@@ -1,5 +1,6 @@
+#Sat May 20 08:51:38 BST 2017
 distributionBase=GRADLE_USER_HOME
 distributionPath=wrapper/dists
 zipStoreBase=GRADLE_USER_HOME
 zipStorePath=wrapper/dists
-distributionUrl=https\://services.gradle.org/distributions/gradle-2.14.1-all.zip
+distributionUrl=https\://services.gradle.org/distributions/gradle-4.0-milestone-1-all.zip