Spring Boot Testing Facilities

[pfrank13]

I created issue #217 that goes over this in more detail. I'd like to point out a few things about the pull request:

1. Upgrades Spring's version and adds a Spring Boot version that matches, this was needed because the latest Spring Boot requires changes in AnnotationUtils that is present in the version it was meant to use (go figure =))
2. I couldn't suss out what was going on in AbstractCassandraUnitTestExecutionListener.alternativePath() and because of the requirements of that method I just ignored it, it seems like a convention of data loading that isn't documented nor even used by the project AFAIK
3. I really wanted to break up EmbeddedCassandraServerHelper into a series of factories or the like as it's a static helper that is definitely order dependent in terms of how it needs to be used. For the Spring Boot related work that ordered is expressed in the Java Config EmbeddedCassandraAutoConfiguration, clearly that won't be able to work outside of a spring context, I wanted to refactor but I was trying to limit change, in terms of smell how I'm using that class is definitely strange but it was mostly to maintain behaviors from the existing testing mechanisms present in CassandraUnit.
4. I changed the default value for the configuration file to use the random port configuration as the annotation is meant to be used with a Spring Boot Application in situ, e.g. this won't even work if there isn't a @SpringBootApplication being bootstrapped, this is just the way the Spring Boot Test mechanisms work. This doesn't preclude someone from using their own configuration file either, the Session and Cluster being used by Spring Data Cassandra isn't even port aware because of how it's being bootstrapped.

[jsevellec]

Really thanks for your the contribution, I'll have a look asap

[asarkar]

You might be interested in my library cassandra-unit-spring that makes testing with Spring Boot/Spring Data a no-brainer.