Peer configuration management (#69)

* feature: add config properties to the SyncResponse of the management gRpc service

* fix: lint errors

* chore: modify management protocol according to the review notes

* fix: management proto fields sequence

* feature: add proper peer configuration to be synced

* chore: minor changes

* feature: finalize peer config management

* fix: lint errors

* feature: add management server config file

* refactor: extract hosts-config to a separate file

* refactor: review notes applied to correct file_store usage

* refactor: extract management service configuration to a file

* refactor: simplify management config

management/server/testdata/management.json

@@ -0,0 +1,25 @@
+{
+    "Stuns": [
+        {
+            "Proto": "udp",
+            "URI": "stun:stun.wiretrustee.com:3468",
+            "Username": "",
+            "Password": null
+        }
+    ],
+    "Turns": [
+        {
+            "Proto": "udp",
+            "URI": "turn:stun.wiretrustee.com:3468",
+            "Username": "some_user",
+            "Password": "c29tZV9wYXNzd29yZA=="
+        }
+    ],
+    "Signal": {
+        "Proto": "http",
+        "URI": "signal.wiretrustee.com:10000",
+        "Username": "",
+        "Password": null
+    },
+    "DataDir": ""
+}