adding first solr integration as part of issue #9

This PR requires a local installation of Solr using the schema provided in the `src/test/resources/index/schema.xml` file. The connection details are kept in `src/main/resources/mamute.properties` file. First step towards #9 
is there a reason to support not-embedded solr? If not, we could just make a feature-toggle key like `feature.search` or something like this