Add %s to certain strings in translations

[Kwpolska]

Via Saadat M. on the mailing list.

Strings:

• More posts about (added %s)
• Also available in (added :)
• Posted (added :)

Change in:

• .py translations
• .po translations (WARNING: will assume that all languages put %s at the end of each string)
• built-in themes
• themes from the index (also pending a re-jinjification)

Languages that will be broken:

• Persian (three strings are likely to be grammatically incorrect)
• Japanese (one that may be grammatically incorrect)
• Chinese (one string that may be grammatically incorrect)
• Urdu (one new empty string)