Версия 200-773

Release notes:

• refactor some more screens to allow creating previews
• refactor all screens to allow creating previews
• fix bug, which allows to go back from internships screen to login screen
• add previews to some screens
• fix navigation
• add app version and some strange shit to app
• add service to check for update and download update
• add new permission and some strange shit to the manifest
• install dependency to install applications
• add representation of local file with mime type and file name and util to install it, if it's application
• update menu screen: add possibility to check for app's updates and install it
• allow customizing http request when downloading
• migrate from system's download manager to custom implementation on dowloading files
• add component for downloading files
• use new button on menu screen
• add help function to open local file
• use new download button on file screen
• move button labels to arguments to make it customizable; override labels in update sheet
• added a check for the existence of a file to avoid re-downloading files
• change downloading path to application's internal, since android is douche bag
• fix to correct version
• add stuff to manipulate notifications
• add spawning notifications when downloading files started
• refactor PermissionManager
• move file where it's belongs to
• rename action
• add action to publish stable release on push to master