replace selmer with enlive

[joyheron]

Currently we use Selmer as a templating engine, but there are some limitations to what we can do with Selmer (for instance, it's very difficult to add custom functions to the templates and do data transformation from within the templates (we need to do it before we pass our data structure into the template).

Also, it is a bit cumbersome to use namespaced keywords within Selmer templates.

We should do a spike to see how it feels to use enlive instead of Selmer as a templating language. This might solve the problem that we currently have to drop the keywords for our view model, and would give us more flexibility to use clojure functions directly in the UI (e.g. being able to use the bidi/route-for function directly in the templates instead of having to construct URIs beforehand and then pass them into the data object).