fixes gh-766

More often than not what Route.path was used it had to be concatenated
with the prefix. This change just encapsulates that concern in the
Route itself.

If it returns Routes instead of Strings it's a lot more obvious
what it's supposed.

Added @FeignClient(fallback).

Renamed FeignClientFactory to FeignContext.

fixes gh-762

fixes gh-727

The RouteLocator interface wasn't very useful to anyone in its
1.0.x form. If ProxyRouteLocator features are consolidated into
the RouteLocator interface then users can supply their own
strategies more easily.

Also added RefreshableRouteLocator for implementations that need
to recompute routes when something changes. SimpleRouteLocator
doesn't need to do that because all the routes are in the configuration.

Added spring-cloud-starter-archaius so downstream projects
like consul and zookeeper don't need to maintain the list of
archaius depenencies.

fixes gh-765

Servo and Spectator metrics defer to other Counter/GaugeServices

This move should be transparant to users of spring-cloud-starter-eureka.

fixes gh-579

The new module is a BOM that doesn't have any parent or direct
dependency management in spring-boot-*. So users can include it
in their dependency management without polluting the spring boot
dependency versions.

Luckily it can also be used in the main spring-cloud-netflix pom,
which should no longer be used as a BOM.

Allows for more fine-grained configuration of what to ignore.

Introduce ServerIntrospector.getMetadata(Server).

fixes gh-419

This reverts commit 721fdc59.