[feature request] support GNU Ring, not Signal

~~GNU Ring~~ **Jami** is the de facto non-controversial secure IM tool for tree-hugging hippy freedom lovers and has support on phones and desktops. The Android app is on f-droid.org. This is a conflict-free open community tool that should be supported.

Signal is apparently supported because of its popularity and/or Snowden's endorsement. But it's a poor choice for many reasons:

* Signal forces Android users into the private walled-garden of Google Playstore just to obtain the APK blob, which is unavailable outside of that jail; consequently:
** excludes people who bought an Android w/out a PlayStore (tm) license
** excludes people who refuse to give their phone number to Google (to create the required acct)
** abuses user privacy through Google tracking (Google keeps track of apps you download and your IMEI number)
** denies source code (most likely... I've not done a thorough search though)
* Signal's Debian release is unofficial. This is likely because it would not pass the quality scrutiny of Debian repository inclusion. It also means users have to do manual steps for the installation.
* Signal's Debian installation is broken (404 error on the package URL). And the "debian" install instructions are actually for Ubuntu.
* Signal's support page is CloudFlared, which:
** subjects people to a private walled-garden that blocks Tor users (a net neutrality abuse)
** and abuses the privacy of those who can use the page by sharing all traffic with CloudFlare Inc., whilst deceiving those users at the same time by showing them an SSL padlock (the tunnel actually terminates at CloudFlare's server not that of the webhost).

That's a lot of evil right there. I suggest:
* giving a low priority to fixing any non-security-critical Signal bug reports (glad to see this seems to already be happening)
* ditching Signal support when a security-critical Signal bug is discovered
* giving a high priority to implementing a GNU Ring feature

# (update) The above is obsolete. See https://github.com/privacytoolsIO/privacytools.io/issues/779 for current OWS Signal privacy abuses

The issue names no files, tests, or entry points; start by locating the Android app's integration boundaries and determine what supporting GNU Ring/Jami would mean for Haven. Confirm scope and acceptance criteria before estimating implementation, since the request is broad and the thread is old.

Written by the indexing model from the issue text.