Update gradle and gradle-plugin to support Android Studio 3.1.

Author: codezjx

.travis.yml

@@ -14,7 +14,7 @@ android:
     - android-26
 
     # The BuildTools version used by your project
-    - build-tools-26.0.2
+    - build-tools-27.0.3
 
     # Additional components
     - extra-android-support

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 'com.github.dcendents:android-maven-gradle-plugin:1.5'
         classpath 'com.jfrog.bintray.gradle:gradle-bintray-plugin:1.7.1'
 

gradle/wrapper/gradle-wrapper.properties

@@ -3,4 +3,4 @@ distributionBase=GRADLE_USER_HOME
 distributionPath=wrapper/dists
 zipStoreBase=GRADLE_USER_HOME
 zipStorePath=wrapper/dists
-distributionUrl=https\://services.gradle.org/distributions/gradle-4.1-all.zip
+distributionUrl=https\://services.gradle.org/distributions/gradle-4.4-all.zip