Add `role="button"` to transaction start links

![](https://s3.amazonaws.com/f.cl.ly/items/1g3M2X3K1F1D3N1c2J1B/Screen%20Shot%202014-12-08%20at%2011.38.44.png)

The 'Start now' buttons on all start pages are often actually links styled to look like buttons. This means that to Assistive Technology (AT), which reads the document based on its HTML rather than its visuals, they are declared as something different to their appearance.

Léonie Watson suggested adding the 'role' attribute, set to 'button', which should give a better experience to users of AT

- Allows users of AT to use space bar and enter, and appropriately signals a button for such users
- Adds it in as the last attribute, not sure if we care about ordering
Add `role="button"` to all elements acting like a `<button>`

![](https://s3.amazonaws.com/f.cl.ly/items/2l2C1F3M0p1o3C3j3v02/Screen%20Shot%202014-12-08%20at%2011.46.46.png)

- This should help users of Assistive Technology get to start buttons quicker, and allows use of space bar OR enter to activate the start button link.
- Adds `role="button"` to all elements that operate as a `<button>` but are e.g. anchor links or inputs with `type="submit"`
- All actual `<button>` elements have been left alone, as I'm assuming there's no need to add a role here