Fix dependencies not supporting Node < v4

Author: SBoudrias

package.json

@@ -52,10 +52,10 @@
     "mem-fs-editor": "^2.0.0",
     "mkdirp": "^0.5.0",
     "nopt": "^3.0.0",
-    "path-exists": "^3.0.0",
+    "path-exists": "^2.0.0",
     "path-is-absolute": "^1.0.0",
     "pretty-bytes": "^3.0.1",
-    "read-chunk": "^2.0.0",
+    "read-chunk": "^1.0.0",
     "read-pkg-up": "^1.0.1",
     "rimraf": "^2.2.0",
     "run-async": "^2.0.0",
@@ -72,7 +72,7 @@
   "devDependencies": {
     "gulp": "^3.6.0",
     "gulp-coveralls": "^0.1.0",
-    "gulp-eslint": "^3.0.1",
+    "gulp-eslint": "^2.0.0",
     "gulp-exclude-gitignore": "^1.0.0",
     "gulp-istanbul": "^1.0.0",
     "gulp-mocha": "^2.0.0",