Upload feature fixes

[ShresthPratapSingh]

This PR completes the upload feature #239 .

The user can now add images, videos and documents. (#233 )

### This PR will close PR #244

*After merging feature/upload can be tested and then finally merged in beta.

[cpg]

Nothing can be read in iOS 12. Also, pushing one (not sure which one) of the icons, there is a crash:

...
AppDelegate.swift: syncWithUserDefaults() - Notifications on? false
2020-07-03 00:54:12.947107+0200 AmahiAnywhere[8424:4245927] *** Terminating app due to uncaught exception 'NSGenericException', reason: 'Your application has presented a UIAlertController (<UIAlertController: 0x1061be600>) of style UIAlertControllerStyleActionSheet from RootContainerViewController (<RootContainerViewController: 0x105813ea0>). The modalPresentationStyle of a UIAlertController with this style is UIModalPresentationPopover. You must provide location information for this popover through the alert controller's popoverPresentationController. You must provide either a sourceView and sourceRect or a barButtonItem.  If this information is not known when you present the alert controller, you may provide it in the UIPopoverPresentationControllerDelegate method -prepareForPopoverPresentation.'

[ShresthPratapSingh]

@cpg I've resolved the conflicts and crashes. This PR is ready to merge.

[ShresthPratapSingh]

@cpg I've changed the base to beta and resolved the conflicts. Ready to merge.