Add basic impersonation support for admins

api/system/spec.json

@@ -19,6 +19,22 @@
         "path": "/check",
         "parameters": {}
       },
+      {
+        "name": "impersonate",
+        "method": "POST",
+        "title": "Impersonate a user",
+        "path": "/impersonate",
+        "parameters": {
+          "post": [
+            {
+              "name": "userID",
+              "type": "uint64",
+              "required": true,
+              "title": "ID of the impersonated user"
+            }
+          ]
+        }
+      },
       {
         "name": "exchangeAuthToken",
         "method": "POST",

api/system/spec/auth.json

@@ -21,6 +21,28 @@
       "Path": "/check",
       "Parameters": {}
     },
+    {
+      "Name": "impersonate",
+      "Method": "POST",
+      "Title": "Impersonate a user",
+      "Path": "/impersonate",
+      "Parameters": {
+        "post": [
+          {
+            "name": "userID",
+            "required": true,
+            "title": "ID of the impersonated user",
+            "type": "uint64"
+          },
+          {
+            "name": "expire",
+            "required": false,
+            "title": "expiration time in seconds, must be shorter than 24h",
+            "type": "int"
+          }
+        ]
+      }
+    },
     {
       "Name": "exchangeAuthToken",
       "Method": "POST",