Fix #733
@ZeHiro, can you have a look, please?
- commit 1 fixes an issue in the loading spinner.
- commit 2 fixes the migration issue observed in #733 (closed), by checking orphan alerts/operations in m16, and re-running m16 in m17 to bypass the migration version check (it's a hack, but oh well). Also, we now re-run migrations until they pass, by returning true/false to indicate the status of the migration. I've run this on my own kresus data, works fine.