Updated dependencies to include Apache HTTP Components for accissing
resources via HTTP
Stylistic improvements.
Broke down retriever instances into Ephemeral and Persistent - allowing
for local data access as well as the ability to persist retrieved data.
Added Default Guice modules for extension points to ensure that the
binding type is properly set, even when no implementations are bound.
That may also provide fail-fast characteristics for extension modules
that bind using the wrong mechanism since Guice may fail to create the
injector.