default prefixes

[nbittich]

No description provided.

[nvdk]

I quite like the idea of supporting prefixes, but I think the implementation needs to be different. Rather than adding the prefixes in the sparql queries I think we need to expand the prefixes on reading the config. This might be done in https://github.com/mu-semtech/mu-search/blob/master/lib/mu_search/property_definition.rb#L10 .

This is required because we will not get prefixed predicates from delta's for example

[nvdk]

@nbittich you may want to have a look at #98 and see if it works for you