Adds deprecation warning to starters

Document untrusted certificates when connecting to hystrix.stream endpoint

This moves the lifecycle of the eureka client of of EurekaServiceRegistry.

fixes gh-2099

Otherwise useServlet31 was always returning false.

fixes gh-2196

Signed-off-by: João Salavessa <joao.salavessa@sky.uk>

Fixes gh-2125

Centralizing HTTP client creation and configuration

(Updated okhttp3 from v3.6.0 to v3.8.1)

They are all deprecated but that's no reason to break them.

Fixes gh-665

Fixes gh-1849

fixes #1741

On certain platforms and compilers the generated bytecode is not what
the configuration expected. By moving inner classes to the upper level
and using @Import this will guarantee the proper order.

fixes gh-2086

On certain platforms and compilers the generated bytecode is not what
the configuration expected. By moving inner classes to the upper level
and using @Import this will guarantee the proper order.

fixes gh-2086

fixes gh-1943

Needed in `EurekaClientConfigBean` because `CloudEurekaTransportConfig` is a separate class.

Fixes gh-2138