Display IPFS addresses instead of opening uploaded file

[lidel]

Part of UX improvements for sharing local files (#342)

Current Behaviour

1. user opens Upload Screen via browserAction
2. user uploads a file (eg. image)
3. upload is successful
4. upload tab is closed (automatically)
5. uploaded file is opened from IPFS address in a new tab (automatically)

This works fine for things like images and videos, but try uploading .zip file 🙃
The browser will display "Save file as..." monit and start download in background. This is very painful if user uploaded huge file, and quite annoying if all user wants is to copy shareable link. (solved in #349)

Expected Behaviour

1. user opens Upload Screen via browserAction
2. user uploads a file (eg. image)
3. upload is successful
4. we stay on the Upload Screen
   it gets updated and presents new items to the user:
   1. Original name(s) of uploaded file(s)
   2. Canonical IPFS path
   3. Shareable URL at public gateway (which user can already customize via Preferences)
   4. "Drop / Upload Another File"

The old behaviour will be just one click away,
but we solve some pressing issues:

• mobile connections with data cap will not charge user twice
• sharing IPFS links to binary files gets a lot easier

Additional Improvements

1. Display indicator of health (peer count of each file obtained via ipfs dht findprovs)
   (ipfs dht findprovs QmbWqxBEKC3P8tqsKc98xmWNzrzDtRLMiMPL8wBuTGsMnR -n 2, then -n 3 etc)
2. A short disclaimer informing uploader/receiver that public gateway does not guarantee availability of content after X hours

(see ipfs/ipfs-gui#34 (comment) for more detailed list)

[lidel]

Design aspect of this is currently tracked in ipfs/ipfs-gui#34
There is also a PoC standalone app: https://github.com/tableflip/share-via-ipfs

---

Q3 2018 Update:

• We are working on an app that will deliver this in: https://github.com/ipfs-shipyard/ipfs-share-files
• The end goal is to bundle it with Companion and replace current upload screen.

[lidel]

Closed in v2.10.0 by opening imported file in Web UI's Files interface: #810