reciprocity/ggrc-core — pull request #1220 by danring (2014-04-05 01:45:47+00:00)
Title: Add `addclass` helper to live-bind additive classes

* Adding classes within the `class` attribute will cause any
externally-added classes to be lost after the bound value changes.
With `addclass`, we instead bind to the attribute/compute explicitly
and add/remove the class as it changes.
* `addclass` will also unbind its callback if the element is detached
from the DOM.