Add gift card template

Adding the default gift card template.

Must be merged __after__ #179 since it is already internationalized.

cc @carolineschnapp @jonasll @stevebosworth 
This is actually the default gift card template that gets generated for you. It styles everything with IDs from a global asset.

I'm thinking I'll strip out the global asset and put the styles into `timber.scss.liquid` as a new section. This will let us have control over almost all naming conventions on the page.