Gradle 修改 Maven 仓库地址

修改 Gradle Maven 仓库地址为阿里云镜像
修改根和子目录下的 build.gradle 文件，追加阿里云仓库：

buildscript {
    repositories {
        maven { url 'http://maven.aliyun.com/nexus/content/groups/public/' }
        maven { url  "https://urbanairship.bintray.com/android" }
        jcenter()
    }
    dependencies {
        classpath 'com.android.tools.build:gradle:2.2.3'
// NOTE: Do not place your application dependencies here; they belong
// in the individual module build.gradle files
    }
}
allprojects {
    repositories {
        maven { url 'http://maven.aliyun.com/nexus/content/groups/public/' }
        jcenter()
    }
}