Make it possible to manually start IBus on all locales
We switched from Scim to IBus, see tickets #5624 and #6206. Among the
changes was to always start IBus by default, regardless of login locale.
But problems with keyboard shortcuts in for example France locale (see
#6478) required a quick fix to not always start IBus by default.
However, after this quick fix it is no longer possible for a user to start
IBus at all in locales other than CJK locales.
I believe I have fixed this issue, and requested a review and merge in: