Merge pull request #11897 from atom/mkt-use-apm-with-npm3-and-node-4

Use apm@1.12.2 with Node v4 and npm v3 \o/

build/tasks/compile-packages-slug-task.coffee

@@ -40,6 +40,8 @@ module.exports = (grunt) ->
       continue if path.basename(moduleDirectory) is '.bin'
 
       metadataPath = path.join(moduleDirectory, 'package.json')
+      continue unless fs.existsSync(metadataPath)
+
       metadata = grunt.file.readJSON(metadataPath)
       continue unless metadata?.engines?.atom?