Milestone: IPFS service

[EDITED]
Serving the files via a local IPFS instance will include:
* Installable IPFS instance - probably JS-IPFS running under node, but could be Go, at some point it has to be installable by non-geeks on a variety of platforms. DONE - though needs autostart
* Main choice criteria might be support for a local filestore rather than duplicating the entire storage requirement, this could probably be hacked onto the JS version fairly easy but may already exist on the Go. I think Protocol calls this module "unixfs" DONE - using urlstore
* Automatically adding all files mirrored to IPFS DONE
* Add some kind of UI (Blocked on #10)
* Startup IPFS at same time as mirrorHttp #22
* Hook /ipfs/Q123 into mirrorHttp #101
* Allow cache and mirrorHttp to fetch files, but careful to avoid loops #100
* Get IPFS working on Rachel #99

Start by checking the still-open checklist items and their referenced issues (#22, #101, #100, and #99), noting that several earlier items are marked DONE and the UI is blocked on #10. The milestone is complete only when the remaining IPFS startup, routing, loop-safe fetching, and Rachel work are resolved.

Written by the indexing model from the issue text.