cmu.oaqa.SolrWrapper -> yodaqa.provider.Solr, based on the original code

The original SolrWrapper had a weird bit about local connection test
that would throw exceptions, plus we relied on a third-party Maven
repository.  Our version of the interface is rather simpler.  This
is all just temporary anyway until we switch to JSolr.
README: Rewrite the initial credits according to current reality