web interfaces: don't include version number in html, only return it after authentication

second round for issue #322

webmail/api.json

@@ -53,6 +53,31 @@
 			"Params": [],
 			"Returns": []
 		},
+		{
+			"Name": "Version",
+			"Docs": "Version returns the version, goos and goarch.",
+			"Params": [],
+			"Returns": [
+				{
+					"Name": "version",
+					"Typewords": [
+						"string"
+					]
+				},
+				{
+					"Name": "goos",
+					"Typewords": [
+						"string"
+					]
+				},
+				{
+					"Name": "goarch",
+					"Typewords": [
+						"string"
+					]
+				}
+			]
+		},
 		{
 			"Name": "Token",
 			"Docs": "Token returns a single-use token to use for an SSE connection. A token can only\nbe used for a single SSE connection. Tokens are stored in memory for a maximum\nof 1 minute, with at most 10 unused tokens (the most recently created) per\naccount.",