Issues 487 - Move Pay Now Butotn + Issue 268 - Offer Categories

Refers to issue 487: https://github.com/oscurrency/oscurrency/issues/487

Changes

* Duplicated the `Pay Now` button, now available below the description
* Color of `Pay Now` button changed to Boostrap Success ( green )

![test app](https://f.cloud.github.com/assets/762159/1762154/b4703240-66ea-11e3-97d8-a9354669ef18.png)

Reffers to issue 268: https://github.com/oscurrency/oscurrency/issues/268

Offer categories are moved to the bottom of each list item and its made horizontal comma separated than been vertical and consuming space.

![test app](https://f.cloud.github.com/assets/762159/1771445/9c715ee4-67b7-11e3-954e-888bea05a0af.png)