fix(bundle): sort bundle files by path

This way we are be sure they will alway be concatenated in the same
order. This is meant to prevent the hash of bundles to change due to an
unexpected order of file inclusion.

lib/build/bundle.js

@@ -136,7 +136,18 @@ exports.Bundle = class {
       });
     }
 
-    work = work.then(() => files = files.concat(this.getBundledFiles()));
+    // Sort files by path to be sure they will alway be concatenated in the same order.
+    let bundleFiles = this.getBundledFiles()
+      .sort((a, b) => {
+        if (a.path > b.path) {
+          return -1
+        } else if (b.path > a.path) {
+          return 1
+        } else {
+          return 0
+        }
+      });
+    work = work.then(() => files = files.concat(bundleFiles));
 
     if (this.append.length) {
       work = work.then(() => addFilesInOrder(this, this.append, files));
@@ -211,7 +222,6 @@ exports.Bundle = class {
             content = Convert.removeMapFileComments(currentFile.contents);
           }
         }
-
         concat.add(currentFile.path, content, sourceMap ? JSON.stringify(sourceMap) : undefined);
       }