Deprecate support for Node.js v0.12

Notes:

  We are deprecating support for Node.js v0.12, to
  be removed in next major version!

index.js

@@ -1 +1,13 @@
-module.exports = require('./src/telegram');
+/**
+ * If running on Nodejs 0.12, we load the transpiled code.
+ * Otherwise, we use the ES6 code.
+ * We are deprecating support for Node.js v0.x
+ */
+const majorVersion = process.versions.node.split('.')[0];
+if (majorVersion === '0') {
+  const deprecate = require('depd')('node-telegram-bot-api');
+  deprecate('Node.js v0.12 and below will no longer be supported in the future');
+  module.exports = require('./lib/telegram');
+} else {
+  module.exports = require('./src/telegram');
+}