[WIP] add Makefile target to initialize the database (bug 1069388)

Fixes [bug 1069388](https://bugzilla.mozilla.org/show_bug.cgi?id=1069388)

Needs the https://github.com/mozilla/schematic/pull/1 PR merged in a branch
named "fake" for the requirements update to work.
Not very explicit but that might be interesting if we have more initial data in the future.