allow Quest Scrolls to be sold for Gold (website and API UI)

Allows a player to sell quest scrolls for gold in the same way that food etc can be sold for gold. Works on Inventory page and through the API Swagger UI.

**Requires PR** https://github.com/HabitRPG/habitrpg-shared/pull/417

Includes a new test in `test/spec/inventoryCtrlSpec.js`. Do not merge if that test fails.

Adds a new style to `public/css/shared.styl` to allow word-wrapping in the blue "sell" button (see image below). Tell me if there's a more preferred way/place to do/put this. Without wrapping, it's a single-line button that stretches well out of the right-hand side of Alexander's box. 

I'll merge this in a couple of days if there's no complaints.

![screen shot 2014-12-29 at 5 14 26 pm](https://cloud.githubusercontent.com/assets/1495809/5566827/1f1dd14c-8f80-11e4-8ae7-c801610516be.png)