Issue 110 : bulkOperations integration tests

Several things to review here :
* the integration tests of course
* some rewrites of the putAll and removeAll methods (with some refactorings too)
Thanks for your input in advance
All lines between beginning of this method (and all others) and this one should become the setup fixture (`@Before`). Then, for the methods that require a writer or loader, you could just reference the `CacheManagerBuilder` field, and append `.using(...)` as needed.