Allow to force a sync in case something went wrong.

[pizzahut2]

For certain sync tasks like the whitelist, it can only be done every 30 days. I somehow lost all whitelist data during or after a recent manual sync. In this case it would be good if it was possible to force another sync, skipping the one month wait.

[pizzahut2]

Loosely related to this, I changed to JustArchi's fork since it doesn't have the 30 day limit - but I'm still having issues with the heart not showing up next to whitelisted people, so forcing a sync isn't a solution which works for me.

[pizzahut2]

So waited a month, synced my whitelist, then wanted to sync my black list ... "you recently synced your white or black list, please disable it" - need to wait another month because I didn't sync whitelist and blacklist together (at the same time).

EDIT: And the whitelist sync cleared ESGST's whitelist data, instead of updating it. Related to this issue, the last page seems to be ok as described there: #1739

EDIT 2: Work-around: Downdate the Firefox addon to v8.8.8 and disable automatic updating of the addon.