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 
Didn't see the `@BeforeClass` method, sorry. We try to leave those `@Before`, `@After` methods before the test cases