Update dependencies, .jshintrc and README

* I updated dependencies and devDependencies.
  * I added [serve-static](https://github.com/expressjs/serve-static) and [serve-index](https://github.com/expressjs/serve-index). According to [the readme of conect](https://github.com/senchalabs/connect/blob/104f475f90ef5c04771c3e0dbbfac0b5b86e5e63/Readme.md#connect-30):

    > Middleware will be moved to their own repositories in the [expressjs](http://github.com/expressjs) organization
  * [cli-color/lib/trim module has been moved to cli-color/trim](https://github.com/medikoo/cli-color/commit/d9fd0aa8a1d6e3a07989c04d9a30ba1a2fa611b8).
  * I removed [gaze](https://github.com/shama/gaze) and [gulp-sass](https://github.com/dlmanning/gulp-sass) because currently this project doesn't use them.
* I updated `.jshintrc`.
  * We don't need to specify the globals of [Mocha](http://visionmedia.github.io/mocha/) explicitly because [JSHint supports `mocha` option](https://github.com/jshint/jshint/pull/1597).
* I updated README.
  * I changed the image format of the fury.io badge from PNG to SVG.
  * I updated the *Contributors* section by running `gulp contribs`.