Sign Android build with Cordova 5

Add the build configuration to sign the .apk file

Add a keystore using:

keytool -genkey -v -keystore example.keystore -alias example -keyalg RSA -keysize 2048 -validity 10000

Note: This should be at root of project. Though not a hard requirement, it eases the file referencing

Add a build.json with release/dev configuration for keystore, at the root of project:

{
  "android": {
    "debug": {
      "keystore": "..\android.keystore",
      "storePassword": "android",
      "alias": "mykey1",
      "password" : "password",
      "keystoreType": ""
    },
    "release": {
      "keystore": "..\android.keystore",
      "storePassword": "",
      "alias": "mykey2",
      "password" : "password",
      "keystoreType": ""
    }
  }
}

Add the —buildConfig switch to Cordova/ Ionic build command:
```
cordova build android --release --buildConfig=build.json
```

or with Ionic as

  ionic build android --release --buildConfig=build.json

The signed file will be generated under the new folder structure at

/platforms/android/build/outputs/apk/android-release.apk