Update mocha in order to make tests run in IE8
Update mocha in order to make tests run in IE8

See
https://github.com/mochajs/mocha/blob/master/CHANGELOG.md#245--2016-01-2
8

date-fns/date-fns,js-fns/date-fns,date-fns/date-fns,js-fns/date-fns,date-fns/date-fns