Consider empty public_endpoint.domains list to be the same as unset

See merge request !266

Renaming all float-related prometheus targets meant that the
"rsyslog.*" job filter was no longer working.

Add a NGINX config option to set X-Robots-Tag:noindex on specific URLs

See merge request !265

Another case of 'if is bad' in NGINX config. Better to just use
a map with a default empty value.

Support new syntax in haproxy

See merge request !258

Classic shell scripting
mistake (http://mywiki.wooledge.org/BashFAQ/050 for instance).

Fix breakage when docker_registry_url is unset.

Do not depend on $XDG_RUNTIME_DIR, which might be unset.

Using "curl -f" means that the authentication call in float-pull-image,
which expects a 401 HTTP status, will not provide the output we need
to extract the www-authentication header.

Fixes issue #137.

Allow customization of ProbeFailure timeouts

Closes #116

See merge request !264

Introduce the new global configuration variable "probe_timeouts_by_probeset".

Support the "prober_labels" service-level attribute, defining
additional labels that will be added to Prometheus prober targets
referring to this service.

Prevent it from going into Skipped state on failure.

Hopefully this way Gitlab will understand that the environment is up
even when "float run" fails.

Just make the CI stop job run sooner than the vmine expiration.