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 
I can make `env` final, but `server` can't be unless I move the `create()` contents into the constructor. Is it alright to just make it private?