updates for jetty 9.1
Adding sample tests for the Person and People resources.
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small cleaning
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added DropwizardClientRule
fixed sample code in javadoc
resolved wildcard imports
Upgrade to Jersey 2.11
Remove old (Jersey 1.x) OptionalFormParamInjectableProvider
Add support for Optional<T> in @FormParam, @CookieParam, and @HeaderParam
Replace PowerMock with reflection in HttpClientBuilderTest

PowerMock doesn't play well with Java 8 and the tests were overly complicated.
The reflection-based approach is more terse but will break if the internals of
the Apache HttpClientBuilder change.
Remove PowerMock from UnitOfWorkApplicationListenerTest
LoggingExceptionMapper should always produce application/json

The LoggingExceptionMapper will fail to produce a valid response and produce
an error if the Content-Type of the Response is not defined as application/json
or any other MediaType for which there is a default renderer for ErrorMessage.
Fix authentication in dropwizard-example
Add toString() method to Saying
Upgrade to SLF4J 1.7.7
Exclude transitive slf4j-api from dropwizard-jackson
Update dropwizard-example @DateRequired filtering