Update ruby -> 2.1.3
Update rails -> 4.1.6
Update gems

A few changes needed to be able to get rid of deprication warnings.

In slim, :attr_delims is depricated and replaced with :attr_list_delims,
https://github.com/slim-template/slim/blob/master/CHANGES#L4

In factorygirl, ignore has been replaced with transient, read more about
it: https://github.com/thoughtbot/factory_girl/pull/651