Supporting Android API 23 (Android 6.0)

If we update build gradle to use ``compileSdkVersion 23``,
``org.apache.http`` package causes error. (issue #4711)

We need to use ``useLibrary 'org.apache.http.legacy'`` to solve this problem.
To use ``useLibrary``, we need to use latest gradle also.

And now, we faced another problem with ``APK Expansion`` java sources.

```
/platform/android/java/src/com/google/android/vending/expansion/downloader/impl/DownloadNotification.java
137 :             mCurrentNotification.setLatestEventInfo(mContext, mCurrentTitle, mCurrentText, mContentIntent); // causes error
```

So, some of APK Expansion java sources are updated by referencing commits from https://github.com/danikula/Google-Play-Expansion-File
And dropped V3CustomNotification.java which was for android 3.0, since godot supports android 14 (4.0) above officially.

Unfortunately, another problem, The 'MissingTranslation' error was occurred.
So, build.gradle is updated to use ``disable 'MissingTranslation'``

Additionally, I updated ``buildToolsVersion``, ``targetSdkVersion`` to latest version.

I tested APK Expansion funtionality on Android 6.0 (Nexus 9, Nexus 6p) and Android 4.4 (Galaxy Note 2)  with Google Developer console.

1 files changed, 6 insertions, 4 deletions

diff --git a/platform/android/build.gradle.template b/platform/android/build.gradle.template
index 9461cd2e99..b960d396ee 100644
--- a/platform/android/build.gradle.template
+++ b/platform/android/build.gradle.template
@@ -3,7 +3,7 @@ buildscript {
 		jcenter()
 	}
 	dependencies {
-		classpath 'com.android.tools.build:gradle:1.2.0'
+		classpath 'com.android.tools.build:gradle:1.3.1'
 	}
 }
 
@@ -25,10 +25,12 @@ android {
 
 	lintOptions {
 		abortOnError false
+		disable 'MissingTranslation'
 	}
 
-	compileSdkVersion 19
-	buildToolsVersion "19.1"
+	compileSdkVersion 23
+	buildToolsVersion "23.0.3"
+	useLibrary 'org.apache.http.legacy'
 
 	packagingOptions {
 		exclude 'META-INF/LICENSE'
@@ -36,7 +38,7 @@ android {
 	}
 	defaultConfig {
 		minSdkVersion 14
-		targetSdkVersion 19
+		targetSdkVersion 23
 	}
 	sourceSets {
 		main {