Sharing beta

Beta release might contains bugs

changes:

1- Implement new UI for picking up a file
2- add search bar to add apps activity
3- do small changes to the UI
4- Fix some bugs
5- Add text to the available download bubble in the web that indicates that there no downloads
6- Fix bug related to changing the app language
7- Add APKS installer to the app so users can send Sharing to the other device and install apks files
8- Fix null link issue when wifi and hotspot and mobile data are off
9- add the ability to cancel files transfer from app
10- add back button to app bar in all sub activities