i18n: translate general templates

[See how to translate a module](https://github.com/inveniosoftware/invenio-i18n/issues/78)

- [x] General templates
  - [x] `body.html`
  - [x] `breadcrumbs.html`
  - [x] `footer.html`
  - [x] `frontpage.html`
  - [x] `javascript.html`
  - [x] `trackingcode.html` 