Add gift card template

Adding the default gift card template.

Must be merged __after__ #179 since it is already internationalized.

cc @carolineschnapp @jonasll @stevebosworth 
Ok makes sense. It's a little confusing now only because `giftcard` is the root name both in the parent module as well as this inner module. In cases like this maybe the parent could be more specific like `giftcard-container` or `giftcard-page-layout` to separate styles related to the page vs reusable giftcard-specific stuff. What do you think?