Handle connection failures in uploads

[fabianfrz]

Actual behaviour

• Tell us what happens
  the file upload stops and no progress is done - It feels like no error handling is happening because of a very long timeout. File Size: 7MB, breaks after 4 to 11 percent.

Expected behaviour

• Tell us what should happen

• the app may reconnect and upload the rest of the file if possible
• try uploads in smaller chunks (for example 0.5 MB)
• fail in a minute if not a single byte is transferred
• If missing: handle connection errors

Steps to reproduce

1. select a list of files
2. click upload

Environment data

Android version:
5
Device model:
Nexus 10
Stock or customized system:
Stock
Nextcloud app version:
3.1
Nextcloud server version:
13