Add optional NPM_TAG param in jenkins release

scripts/release.js

 const isRelease = process.env.RELEASE_BUILD === 'true';
 
 const BRANCH = process.env.BRANCH;
-const VERSION_TAG = isRelease ? 'latest' : 'snapshot';
+const VERSION_TAG = process.env.NPM_TAG || isRelease ? 'latest' : 'snapshot';
 const VERSION_INC = 'patch';
 
 function run() {