Add support custom time format

Hi, It has added a panel to specify custom time format.
In addition, I have updated `Gemfile.lock` because [out-of-date](https://gemnasium.com/Tomohiro/fluentular) alert.

This enhancement made a change for page design like below. (added a panel to show time attribute)
![2014-03-18 17 54 18](https://f.cloud.github.com/assets/1734549/2445860/28b58114-ae7b-11e3-931d-1e4f9def0ee7.png)