Unfortunately with `v-html` you cannot use filters directly in
handlebars.
See: https://github.com/nuxt/nuxt.js/issues/231
I also fixed the tests even **without** mocking vue-filters.js plugin 👍
cc @mattwr18 Please don't see this as a revert of your work. Your
structure of the `notification-post-card` component was helpful and showed
the redundancy with `hc-post-card`. I reused a lot of the code, but
because I merged both components it now *looks* as if I authored all the code.
