this is a Gradle guide to use on all Android applications in general.

build.gradle(app)

apply plugin: 'com.android.application'

Properties local_properties = new Properties()
File localPropertiesFile = project.rootProject.file('local.properties')
if (localPropertiesFile.exists()) {
    local_properties.load(localPropertiesFile.newDataInputStream())
}

def STRING = 'String'
def GIT_SHA = 'GIT_SHA'
def BUILD_TIME = 'BUILD_TIME'
def gitSha = 'git rev-parse --short HEAD'.execute([], project.rootDir).text.trim()
def buildTime = new Date().format("yyyy-MM-dd'T'HH:mm'Z'", TimeZone.getTimeZone("UTC"))

android {

    publishNonDefault true
    compileSdkVersion rootProject.ext.compileSdkVersion
    buildToolsVersion rootProject.ext.buildToolsVersion

    defaultConfig {
        applicationId "co.mobiwise.project_name"
        minSdkVersion rootProject.ext.minSdkVersion
        targetSdkVersion rootProject.ext.targetSdkVersion
        versionCode rootProject.ext.versionMajor * 10000 + rootProject.ext.versionMinor * 1000 + rootProject.ext.versionPatch * 100 + rootProject.ext.versionBuild
        versionName "${rootProject.ext.versionMajor}.${rootProject.ext.versionMinor}" + ((rootProject.ext.versionPatch != 0) ? ".${rootProject.ext.versionPatch}" : "")
        buildConfigField STRING, GIT_SHA, "\"${gitSha}\""
        buildConfigField STRING, BUILD_TIME, "\"${buildTime}\""
        buildConfigField INT, DATABASE_VERSION, '1'
        buildConfigField INT, CONNECTION_TIMEOUT, '2000'
        buildConfigField BOOLEAN, IS_DOGFOOD_BUILD, FALSE
    }

    signingConfigs {
        debug {
            storeFile file("../distribution/debug.keystore")
        }

        release {
            storeFile file("../distribution/" + (local_properties.release_keystore_name ?: "debug.keystore"))
            keyAlias(local_properties.release_keystore_alias ?: "androiddebugkey")
            storePassword(local_properties.release_keystore_pwd ?: "android")
            keyPassword(local_properties.release_keystore_pwd2 ?: "android")
        }
    }

    buildTypes {
        debug {
            applicationIdSuffix ".debug"
            buildConfigField BOOLEAN, IS_DOGFOOD_BUILD, TRUE
            buildConfigField STRING, LOG_PREFIX, '"co.mobiwise.project_name"'
            buildConfigField INT, CONNECTION_TIMEOUT, '5000'
            buildConfigField STRING, DATABASE_NAME, '"debug_tcm_sfa.sqlite"'
            minifyEnabled false
        }
        release {
            buildConfigField STRING, LOG_PREFIX, '"co.mobiwise.project_name"'
            buildConfigField STRING, DATABASE_NAME, '"co.mobiwise.project_name.sqlite"'
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
        }
    }
}

dependencies {
    compile fileTree(dir: 'libs', include: ['*.jar'])
    compile 'com.android.support:appcompat-v7:22.2.0'
    compile 'com.squareup.retrofit:retrofit:1.9.0'
    compile 'com.squareup.okhttp:okhttp-urlconnection:2.0.0'
    compile 'com.squareup.okhttp:okhttp:2.0.0'
    compile 'com.squareup:otto:1.3.8'
    compile 'com.android.support:design:22.2.0'
    compile 'com.squareup.picasso:picasso:2.5.2'
    compile 'com.google.code.gson:gson:2.2.4'
    compile 'com.android.support:recyclerview-v7:22.1.1'
    compile 'com.android.support:cardview-v7:22.1.1'
    compile 'com.jakewharton:butterknife:7.0.1'
    compile 'com.j256.ormlite:ormlite-android:4.48'
}

build.gradle(in root)

buildscript {
  repositories {
    jcenter()
    mavenCentral()
    mavenLocal()
  }
  dependencies {
    classpath 'com.android.tools.build:gradle:1.3.0-beta3'
    classpath 'com.github.ben-manes:gradle-versions-plugin:0.11.3'
  }
}

apply plugin: 'com.github.ben-manes.versions'

allprojects {
  repositories {
    jcenter()
    mavenCentral()
    mavenLocal()
    
  }
}

ext {
  preDexEnabled = "true".equals(System.getProperty("pre-dex", "true"))

  versionMajor = 1
  versionMinor = 0
  versionPatch = 0
  versionBuild = 0

  compileSdkVersion = 22
  buildToolsVersion = "22.2.0"
  targetSdkVersion = 22
  minSdkVersion = 9
}