Wesby templates

**Changes**
* + Adds a web service to retrieve the data in Json format
* + Adds Javascript templating
  * Templates can be stored in a directory and bind to the resources in a config file
  * Data can be access with Javascript and mustache
* + Adds a progress indicator to give a visual clue about the data retrieval progress
* + Main body of the page and data are loaded separately, so that the page is served faster.
* - Removes the compiled templates engine

**Work to be done:**
* Dereference RDF URIs from the domain.
* Templates directory definition in config file
* Allow retrieval of relations with the form `?s resource ?o`
* Improve data retrieval speed when the data is not cached
* Write more tests