Add isDebugEnabled() for logging operations

If the management.port is explicitly set to something other than the
server.port, we can use it to set the status page and health URL
default values. (They can still be overridden by config properties.)

If management.port=0 there's not much we can do because we don't know
the port number yet when the instance config is created.

Fixes gh-425

The aspectjweaver jar includes all of aspectjrt, and the former is
used at runtime in a number of places (tests fail if you remove
it). Both are not needed so we have picked one (the other one than
recommended in gh-666).

Fixes gh-666

fixes gh-591

EurekaBootStrap implements ServletContextListener which causes problems because of early instantiation.

fixes gh-664

* pull625:
  Refactor SimpleHostRoutingFilter

Removed deprecated HttpClient APIs, exposed method to override client, fixed ignoredHeaders

* multiple_monitoring:
  Enables hystrix monitoring of multiple services on a single server.

* create-httpclient-ribbon-command:
  an Apache http client zuul ribbon command

This is an implementation of a RibbonCommand and a factory which makes
use of a loadbalancing http client based on apache's http-components
http-client.
With this command/factory it is possible to route PATCH http requests
via zuul/ribbon as well.

fixes gh-412

* pull655:
  Add support for placeholders in @FeignClient definitions

Includes name and url attributes.

fixes gh-414

fixes gh-657

fixes gh-651

fixes gh-623

Logging each request in the proxy is too verbose and inconsistent
with other Spring MVC logging.

* metrics-aop-fix:
  RestTemplate metrics collection join point now returns a value

Also changes pointcut to use the interface so you don't need
proxyTargetClass=true.

Fixes gh-636

fixes gh-635

* feign-no-content-test:
  Feign handling unparameterized ResponseEntity

fixes gh-612

so that Eureka InstanceInfo (which is designed to be immutable)
can effectively be mutated (by using a different instance) after the
dynamic port is available.

fixes gh-570 ... again

Reword to avoid broken AsciiDoc formatting.

Allows non-eureka based InstanceDiscovery.
Allows custom InstanceDiscovery.

fixes gh-566

fixes gh-589

* metrics-test-fixes:
  Fix flaky Servo tests by avoiding DefaultMonitorRegistry