upgrade the gradle version

Author: HelloHuDi

build.gradle

@@ -1,13 +1,13 @@
 // Top-level build file where you can add configuration options common to all sub-projects/modules.
 
 buildscript {
-    ext.kotlin_version = '1.2.20'
+    ext.kotlin_version = '1.2.31'
     repositories {
         google()
         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 'com.github.dcendents:android-maven-gradle-plugin:1.5'
         classpath 'com.jfrog.bintray.gradle:gradle-bintray-plugin:1.7.3'

gradle/wrapper/gradle-wrapper.properties

@@ -1,6 +1,6 @@
-#Tue Feb 06 08:59:26 CST 2018
+#Tue Apr 10 13:43:54 CST 2018
 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