Successfully launched vanilla minecraft, however much code cleanup is pending.

app/assets/js/library.js

@@ -0,0 +1,37 @@
+
+exports.mojangFriendlyOS = function(){
+    const opSys = process.platform
+    if (opSys === 'darwin') {
+        return 'osx';
+    } else if (opSys === 'win32'){
+        return 'windows';
+    } else if (opSys === 'linux'){
+        return 'linux';
+    } else {
+        return 'unknown_os';
+    }
+}
+
+exports.validateRules = function(rules){
+    if(rules == null) return true
+
+    let result = true
+    rules.forEach(function(rule){
+        const action = rule['action']
+        const osProp = rule['os']
+        if(action != null){
+            if(osProp != null){
+                 const osName = osProp['name']
+                 const osMoj = exports.mojangFriendlyOS()
+                 if(action === 'allow'){
+                     result = osName === osMoj
+                     return
+                 } else if(action === 'disallow'){
+                     result = osName !== osMoj
+                     return
+                 }
+            }
+        }
+    })
+    return result
+}