Updated translation templates and removed en translations

"en" translations have been mistakenly committed in 87cc3da81.
Added myself to the committers list.
Used ngettext in a formsets error message

Several languages will distinctly translate '%d or fewer forms'
depending on the variable.
Systematically imported wraps from functools
Fixed #18351 -- Added X-Robots-Tag header to sitemaps

Thanks Michael Lissner for the report and initial patch, and
Tom Mortimer-Jones for working on the patch.
One more changed import location of wraps