Remove raindrop_tag variable

[mwainwright]

As things have turned out, the raindrop_tag variable is not a very helpful feature, since most (all?) things not vetted for posting to twitter are in a different collection anyway. So in practice the result is just that things don't get posted if the tag has been left off by mistake.

I'd suggest removing the feature, or else allowing everything to be selected if the tag is unset (or if this is already the case, clarify this in the documentation).

If the tag is retained, I'd suggest a more descriptive name for the variable, e.g. twitter_tag instead of raindrop_tag. All tags in Raindrop are Raindrop tags, after all.

[mwainwright]

Conceivably more useful in future would be a tag with the effect "Don't post to Twitter", though I'm not aware of a need for it at the moment.

[edsaperia]

You found a way to bulk add tags right? So we can close this issue?