Move package.ignore contents to package.json

This allows `Makefile` to require and join the ignore entries easily
with NodeJS instead of relying on `tr` and `sed`.

Makefile

@@ -1,6 +1,6 @@
 ELECTRON_PACKAGER=./node_modules/.bin/electron-packager
 ELECTRON_BUILDER=./node_modules/.bin/electron-builder
-ELECTRON_IGNORE=$(shell cat package.ignore | tr "\\n" "|" | sed "s/.$$//")
+ELECTRON_IGNORE=$(shell node -e "console.log(require('./package.json').packageIgnore.join('|'))")
 ELECTRON_VERSION=0.36.8
 ETCHER_VERSION=$(shell node -e "console.log(require('./package.json').version)")
 APPLICATION_NAME=$(shell node -e "console.log(require('./package.json').displayName)")

package.ignore

@@ -1,21 +0,0 @@
-LICENSE
-Makefile
-package.ignore
-(.*)\.md
-appveyor.yml
-bower.json
-gulpfile.js
-screenshot.png
-tests
-etcher-release
-lib/scss
-node_modules/electron-mocha
-node_modules/electron-builder
-node_modules/angular-mocks
-node_modules/browserify
-node_modules/gulp*
-node_modules/jshint-stylish
-node_modules/mochainon
-node_modules/vinyl-*
-node_modules/rindle
-node_modules/tmp

package.json

@@ -17,6 +17,28 @@
   },
   "author": "Juan Cruz Viotti <juan@resin.io>",
   "license": "Apache-2.0",
+  "packageIgnore": [
+    "LICENSE",
+    "Makefile",
+    "(.*)\\.md",
+    "appveyor.yml",
+    "bower.json",
+    "gulpfile.js",
+    "screenshot.png",
+    "tests",
+    "etcher-release",
+    "lib/scss",
+    "node_modules/electron-mocha",
+    "node_modules/electron-builder",
+    "node_modules/angular-mocks",
+    "node_modules/browserify",
+    "node_modules/gulp*",
+    "node_modules/jshint-stylish",
+    "node_modules/mochainon",
+    "node_modules/vinyl-*",
+    "node_modules/rindle",
+    "node_modules/tmp"
+  ],
   "builder": {
     "osx": {
       "title": "Etcher",