Merge branch 'httpFileUpload' of https://github.com/worlword/converse.js into worlword-httpFileUpload

If "inVerse" is renamed to "fullscreen" then "inVerse" in the fullscreen.html file should be renamed to "Converse"?

This reverts commit 7303e96c.

Instead of dropping the feature entirely, we can check if the CSN is a
carbon message.

used code from 'http-file-upload' branch. Buttons are now added to the toolbars through converse-http-file-upload.js.

To avoid showing them erroneously would mean keeping track of used
message ids which seems like more work than justified by the feature.

Fixes #1026

To more cleanly separate views and models and to make MUC in headless
mode more viable.

Refs #1032

* Distinguish between CSN messages and other types of messages
* Properly clear previous notifications
* Better handling of notifications from multiple users (in MUC)
* Rename methods to make clarify intent

* replace geoURIs by link to openstreetmap

* Added testcase