Since a HEAD request to the heapdump triggers a dump we need to test the
availability of the heapdump endppoint via OPTIONS-request.
To get this working we need to ensure that the OPTIONS-request are dispatched
to the zuul servlet as this wasn't done prio to this commit adding the
OptionsDispatchingZuulController.

Update quick start doc link to 1.3.4

With this commit you can from now on register the application on multiple
servers. You need to set spring.boot.admin.register-once to false and
assign a list of urls to spring.boot.admin.url

fixes #230

Detecect endpoints by making a HEAD request instead of querying the configprops
since it is broken when having a second applicationContext

fixes #226

Sometimes Eureka only provides only the securedhealthUrl for the service.
Previous to this commit the applciation won't be registered in that case. So
with this commit the securedHealthUrl from Eureka is used, when available

fixes #224

With this commit urls form the /info endpoint are deteceted and rendered as
links.
The downside is to make that work I had to drop the collapsible info section in
the overview list and replaced it with an resizable/scrollabe <pre> section.

Don't refer to fonts.googleapis.com for the fonts so that using the ui behind a
corporate proxy isn't such a pain anymore.

fixes #213

Checks the DiscoveryClient's services on each heartbeat and removes all
services, which are no longer registered.

fixes #214