upgrade jingo to 0.7 (again: reverts the revert in 61c4359) (bug 976727)
overload jingo.helpers.f to fix UnicodeEncodeError (bug 976727)
Merge pull request #1834 from magopian/976727-jingo-upgrade-unicode-error

re-upgrade jingo to 0.7, overload jingo.helpers.f to fix UnicodeEncodeError (bug 976727)