When packages are listed without an explicit version number, this crashes npm-check-updates

[GerHobbelt]

Tested with both 1.5.1 and 2.0.0beta6: running npm-check-updates -u in a directory which contains this package.json:

{
  "name": "na",
  "description": "not relevant.",
  "version": "0.1.0",
  "devDependencies": {
    "cjson": "^0.3.0",
    "docco": "git://github.com/GerHobbelt/docco.git#gh-pages",
    "event-stream": "",
    "gulp": "",
    "gulp-closure-compiler": "",
    "gulp-compressor": "",
    "gulp-concat": "",
    "gulp-exec": "",
    "gulp-file-include": "",
    "gulp-insert": "",
    "gulp-jison": "git://github.com/GerHobbelt/gulp-jison.git#master",
    "gulp-jsbeautifier": "",
    "gulp-karma": "",
    "gulp-less": "",
    "gulp-manifest": "",
    "gulp-replace": "",
    "gulp-run": "^1.6.6",
    "gulp-util": "^3.0.3",
    "gulp-yuicompressor": "",
    "jasmine-core": "^2.2.0",
    "jsdoc": "git://github.com/GerHobbelt/jsdoc.git#master",
    "karma-chrome-launcher": "^0.1.7",
    "karma-jasmine": "^0.3.5",
    "mkdirp": "^0.5.0",
    "through2": "^0.6.3",
    "yargs": ""
  }
}