Fixes App Icon and Presplash_Screen For Webview bootstrap (#2556)

* dddd

Signed-off-by: kengoon <kengoon19@gmail.com>

* fix for issue #2552 and presplash_color

Author: kengoon

pythonforandroid/bootstraps/webview/build/templates/AndroidManifest.tmpl.xml

@@ -46,7 +46,7 @@
          An example Java class can be found in README-android.txt
     -->
     <application android:label="@string/app_name"
-                 android:icon="@drawable/icon"
+                 android:icon="@mipmap/icon"
                  android:allowBackup="{{ args.allow_backup }}"
                  {% if args.backup_rules %}android:fullBackupContent="@xml/{{ args.backup_rules }}"{% endif %}
                  android:theme="{{args.android_apptheme}}{% if not args.window %}.Fullscreen{% endif %}"

pythonforandroid/bootstraps/webview/build/templates/strings.tmpl.xml

@@ -2,4 +2,5 @@
 <resources>
     <string name="app_name">{{ args.name }}</string>
     <string name="private_version">{{ private_version }}</string>
+    <string name="presplash_color">{{ args.presplash_color }}</string>
 </resources>