reuse ERROR: prefix in internationalized strings

[nbachiyski]

Move ERROR: out of translatable string in order to be translated only once and concatenate it with different error messages.

[ryan]

I prefer avoiding concats, but we can decide in 2.1.1. I'd like to avoid any more string changes in 2.1.

[nbachiyski]

Can we decide it for sure? It would be very useful for translators to have a string freeze some days before the release. I have relased the beta in Bulgarian and had no problems (except the one with the admin username). Even if there comes up a mistaken string I think we could take the risk and leave it for the next version :)

[rob1n]

Also, why have <strong> in there? That's language independent, right?

[nbachiyski]

Unfortunately we cannot separate them because of rtl languages. We'd better close this one.