Topic/fluent api

I introduced fluent API in EmbeddedMongoFactoryBean. It is completely supported by Spring and allows to use much shorter syntax when configuring Mongo:

```
return new EmbeddedMongoFactoryBean().setVersion(MONGO_VERSION).setPort(MONGO_PORT);
```
instead of

```
        EmbeddedMongoFactoryBean factoryBean = new EmbeddedMongoFactoryBean();
        factoryBean.setVersion(MONGO_VERSION);
        factoryBean.setPort(MONGO_PORT);
        return factoryBean;
```

By the way I changed a version in pom.xml to -SNAPSHOT. It is a good habit to keep -SNAPSHOT version in Git/SCM to prevent accidental override local release artifacts when someone would clone project from Git and call `mvn install`.