Shift server examples to a subdirectory.

--HG--
rename : src/examples/apache_fake.rs => src/examples/server/apache_fake.rs
rename : src/examples/hello_world.rs => src/examples/server/hello_world.rs
rename : src/examples/info.rs => src/examples/server/info.rs
rename : src/examples/request_uri.rs => src/examples/server/request_uri.rs