Improve test coverage

Improves test coverage of the following classes:

* Logger/ElasticaLogger
* Client
* FOSElasticaBundle
* HybridResult
* Repository
* Transformer/ElasticaToModelTransformerCollection

Also:

* Fixes a minor bug in `Logger/ElasticaLogger` where the log method on the decorated logger was called without a log level.

* Removes an unused method - `Transformer/ElasticaToModelTransformerCollection::getTypeToClassMap`