Dynamically build file patterns for release task

- converted release task to function task
- dynamically setting config for copy task by reading `.npmignore` on demand
- speeds up all other tasks because `.npmignore` is no longer read from filesystem

Gruntfile.js

@@ -21,23 +21,6 @@ var _              = require('lodash'),
     mochaPath      = path.resolve(cwd + '/node_modules/grunt-mocha-cli/node_modules/mocha/bin/mocha'),
     emberPath      = path.resolve(cwd + '/core/client/node_modules/.bin/ember'),
 
-    // ## Build File Patterns
-    // A list of files and patterns to include when creating a release zip.
-    // This is read from the `.npmignore` file and all patterns are inverted as the `.npmignore`
-    // file defines what to ignore, whereas we want to define what to include.
-    buildGlob = (function () {
-        /*jslint stupid:true */
-        return fs.readFileSync('.npmignore', {encoding: 'utf8'}).split('\n').map(function (pattern) {
-            if (pattern[0] === '!') {
-                return pattern.substr(1);
-            }
-            return '!' + pattern;
-        }).filter(function (pattern) {
-            // Remove empty patterns
-            return pattern !== '!';
-        });
-    }()),
-
     // ## Grunt configuration
 
     configureGrunt = function (grunt) {
@@ -402,16 +385,6 @@ var _              = require('lodash'),
                 }
             },
 
-            // ### grunt-contrib-copy
-            // Copy files into their correct locations as part of building assets, or creating release zips
-            copy: {
-                release: {
-                    expand: true,
-                    src: buildGlob,
-                    dest: '<%= paths.releaseBuild %>/'
-                }
-            },
-
             // ### grunt-contrib-compress
             // Zip up files for builds / releases
             compress: {
@@ -928,7 +901,22 @@ var _              = require('lodash'),
             ' - Copy files to release-folder/#/#{version} directory\n' +
             ' - Clean out unnecessary files (travis, .git*, etc)\n' +
             ' - Zip files in release-folder to dist-folder/#{version} directory',
-            ['init', 'shell:ember:prod', 'clean:release',  'shell:dedupe', 'shell:shrinkwrap', 'copy:release', 'compress:release']);
+            function () {
+                grunt.config.set('copy.release', {
+                    expand: true,
+                    // #### Build File Patterns
+                    // A list of files and patterns to include when creating a release zip.
+                    // This is read from the `.npmignore` file and all patterns are inverted as the `.npmignore`
+                    // file defines what to ignore, whereas we want to define what to include.
+                    src: fs.readFileSync('.npmignore', 'utf8').split('\n').filter(Boolean).map(function (pattern) {
+                        return pattern[0] === '!' ? pattern.substr(1) : '!' + pattern;
+                    }),
+                    dest: '<%= paths.releaseBuild %>/'
+                });
+
+                grunt.task.run(['init', 'shell:ember:prod', 'clean:release',  'shell:dedupe', 'shell:shrinkwrap', 'copy:release', 'compress:release']);
+            }
+        );
     };
 
 module.exports = configureGrunt;