updated Android SDK an sample

- custom sound file
- if title is empty show the app name as title
Updated API to version 1.2

Added methods : GetAppUsersForApp
Added PlatformFeatures for notifications
Modified methods : CreateNotification now returns summeryId, customId
added to Register and Unregister device.
Updated .NET API samples

added a sample for GetAppUsersForApp
Merge branch 'master' of https://github.com/PushAppsService/PushAppsSDK