add mkt-prompt element

![screen shot 2014-12-18 at 6 05 00 pm](https://cloud.githubusercontent.com/assets/674727/5499226/7038bf22-86e0-11e4-9834-51fe33050cce.png)

@mstriemer @spasovski 
Native promises polyfill? Quick search shows [es6-promise](https://github.com/jakearchibald/es6-promise) as a front runner (2.2kB gzipped).