Make it so most Bitcoin donations arrive directly on RiseupLabs' Coinbase account

This will simplify things both for our accounting team and for our fiscal sponsor (RiseupLabs). Ideally we would point most visitors to RiseupLabs’ Coinbase address, and a small fraction of them to our own Bitcoin address, so that we keep some Bitcoin under our own control and can use them directly without converting to a fiat currency first.

Implementation options:

• High-tech: a little bit of JavaScript (very similar to the code that picks a random mirror for downloads) should do the job.
  • pros: do the work once and forget it; the ratio can easily be adjusted dynamically
  • cons: some initial dev work (probably 20-40 SLOC, let’s say 2 hours of work including debugging + review & merge)
  • intrigeri could do it (or find someone else to do it) at some point in 2017, if we decide this is the best option
• Low-tech: point to our own Bitcoin address most of the year, and point to RiseupLabs’ one during our yearly donation campaign.
  • pros: very little work
  • cons: we need to keep track of this forever, to avoid forgetting to switch to the other address when relevant
  • intrigeri is not excited at the idea of tracking all this, but volunteers anyway to create 3 sub-tickets of the 2017 donation campaign: switching to RiseupLabs’ address, switching back, and creating the same tickets for 2018

Feature Branch: web/12268-riseuplab-coinbase

Parent Task: #14877 (closed)

Original created by @intrigeri on 12268 (Redmine)