Reorganize imports.
Apply warning fixes suggested by IntelliJ IDEA.
Don't swallow exceptions when constructing the SSL factory.
Remove the unused SparkTestUtil::getPort.
Avoid strings and booleans in favour of rich types.
Refactored the integration tests to use matchers.

* Use Hamcrest instead of JUnit's static assert* methods.
* Custom UrlResponseMatcher for the UrlResponse class.
Refactored the QueryParamsMapTest to use matchers.
Refactored the RequestTest to use matchers.
Got the BooksIntegrationTest working and refactored it to use matchers.