Providing front-end hooks for the Change/Remove button HTML

Hi,

This pull request extends the front-end options by providing hooks to:
- Wrap the buttons in a HTML string denoted by the option `buttonContainerTemplate`.
- Define the HTML structure of the 'Change' and 'Remove' buttons with the options `changeButtonTemplate` and `removeButtonTemplate` respectively.

The `changeButtonText` and `removeButtonText` can now be set to falsey values in order for them to have no effect.

Cheers,
Mark.