Hello together!

On an IRC talk i saw a link to our coding convention [1] with the hint, that
we use tabs for indentings, so far so good. Now i was wondering, why our
en.json language file (the only one) uses whitespaces, instead of tabs, and
if there was a special reason for this? If not, can we change these to tabs?

Background: My favourite editor doesn’t show any difference between tabs and
whitespaces (sure, more a setting or a „problem“ of the editor), so i had
sometimes the problem, that i forget, that there are whitespaces, instead of
tabs, which ends in a new patchset for a change :) All our files, including
our language files (excluding en.json) uses tabs instead of whitespaces. Now
i suggest to be consistent in en.json, too (if there is no special reason
for it don’t do it) :) Opinions?

[1] https://www.mediawiki.org/wiki/Mobile_web/Coding_conventions