Use StringBuffer for String concatenation

See https://github.com/spring-cloud/spring-cloud-commons/issues/265

Eureka ServerConfiguration is now auto-configuration based, instead of being explicitly specified via configuration pulled in through @EnableEurekaServer. This way specific beans can be conditionally overridden, configuration can be re-ordered.
Supports PeerEurekaNodes bean to be overridden by the user

Fixes gh-1717

fixes gh-1616

Fixes gh-1546

fixes gh-1285

Fixes gh-1205

so they don't appear on the dashboard

Fixes gh-974

Fixes gh-642

fixes gh-589

get's eureka branding back.

fixes gh-627

fixes gh-527

Remove Servo from EurekaHealthIndicator.
Remove custom DataCenterInfo.
EurekaInstanceConfig.SID is now used as eureka id.
EurekaInstanceConfigBean.getSID falls back to metadataMap.instanceId for
backwards compatibility.

Fixes gh-117

fixes gh-100

Blitz4j is definitely preventing the log levels from being changed at runtime
through the normal Spring boot channels.

Fixes gh-48

Blitz4j is definitely preventing the log levels from being changed at runtime
through the normal Spring boot channels.

Fixes gh-48

Most browsers support <base href="..."> these days and there
was one already in statut.ftl (but not in navbar). Added a test
that asserts the css is loadable as well.

Fixes gh-55

All static content is excluded in the Jersey config, so we can use
/eureka for the prefix to the Eureka API (i.e. /apps etc.)

Fixes gh-44