[ja] Support i18n 70-base64 node. (#591)

* [ja] Translate 70-base64 node.

* Fix PR review #591 "Buffer" -> "バッファ".

We have used Japanese katakana words of "buffer" in http-request and file-out nodes.

* Fix PR review #591 "Base64" -> "base64"

* Fix PR review #591 "Base64から文字列へデコード" -> "Base64から文字列へ変換"

parsers/base64/locales/en-US/70-base64.json

@@ -0,0 +1,24 @@
+{
+  "base64": {
+    "base64": "base64",
+    "label": {
+      "action": "Action"
+    },
+    "convert": {
+      "buffer": "Convert Buffer <-> Base64",
+      "encode": "Encode as Base64",
+      "decode": "Convert Base64 to String"
+    },
+    "log": {
+      "nonbase64encode": "Not a Base64 string - maybe we should encode it..."
+    },
+    "warn": {
+      "cannothandle": "This node only handles strings or buffers.",
+      "noproperty": "No property found to process"
+    },
+    "error": {
+      "invalid": "Invalid Base64 string",
+      "nonbase64": "Not a Base64 string"
+    }
+  }
+}