Add support for prometheus 2.0

New version changes:
* different alerts format
* rewritten storage (some config flags removed)

Closes-Bug: PROD-16609
Change-Id: I805fa322e4744e98177d6c3e29589ebc6fb917a2
diff --git a/README.rst b/README.rst
index cee3e90..95be7cc 100644
--- a/README.rst
+++ b/README.rst
@@ -15,6 +15,7 @@
 
   prometheus:
     server:
+      version: 2.0
       enabled: true
       dir:
         config: /srv/volumes/prometheus
@@ -62,11 +63,7 @@
             process_open_fds / process_max_fds
       storage:
         local:
-          engine: "persisted"
           retention: "360h"
-          memory_chunks: 1048576
-          max_chunks_to_persist: 524288
-          num_fingerprint_mutexes: 4096
       alertmanager:
         notification_queue_capacity: 10000
       config: