Make Android build smarter (SCons + Gradle)

Upgrade Gradle and Android plugin for Gradle
Disable all signing and zip-aligning for the export templates
Give correct names to generated APKs
Put .so files built by SCons right where Gradle has to pick them according to arch & build type
Downgrade NDK platform to 14 to match minSdkVersion

platform/android/export/export.cpp

@@ -1166,7 +1166,7 @@ Error EditorExportPlatformAndroid::export_project(const String& p_path, bool p_d
 			skip=true;
 		}
 
-		if (file=="lib/armeabi/libgodot_android.so" && !export_arm) {
+		if (file.match("lib/armeabi*/libgodot_android.so") && !export_arm) {
 			skip=true;
 		}