Moves LookupBySlug controller concern out into a module called
Openvault::SolrHelper. This was done in an effort to avoid having to test
controller mixins, but alas, it depends on Blacklight::SolrHelper which is
designed as a controller layer mixin, so we are sort of tied to doing it like
that, save for some unintuitive work arounds. However, I stuck with moving it
out of app/controller/concerns because:
  a) the more i read about and use Rails-like concerns, the less I like them as
     a common practice, so I don't want to get away from using them.
  b) it more closely resembles Blacklight::SolrHelper, and all we are doing is
     wrapping some of the methods from that module, so it makes sense to follow
	 the same design pattern, even if its not awesome.

Adds a test for the new Openvault::SolrHelper module, although it was a PITA to
write. I'm not a fan of controller mixins after this.

Other somewhat unrelated changes include:
  * pinning country_select to a version that doesn't break with our code.
  * changing some ingester_spec.rb to use rspec 3 syntax (there is still some
    rspec 2 syntax out there)