Fix some build issues

This PR address a couple issues I found whilst trying to build the site the first time.

### Installing gems without bundler

This may be less of an issue to the Rubyist among us, but in my experience install gems globally results is pain pretty quickly. Especially since I personally work with multiple version of sass and compass in any single day.

### Errors running npm install

Executing `npm install` results in errors trying to resolve the `"autoprefixer": "~1.0.20140117"` dependency. Since there doesn't appear be a release that could match this version pattern I've opted to remove it. Is there some reason behind this version @benschwarz @toolmantim ?

### Errors running grunt dev

Executing `grunt dev` results in the following error:

```bash
➜  2014 git:(master) ✗ grunt dev
Running "clean:html" (clean) task

Running "assemble:site" (assemble) task
Fatal error: Object  has no method 'use'
```

I dug into the problem and it's being caused by assemble's permalink plugin. I was able to get the site compiling by commenting out the relevant config. @toolmantim any ideas what's going on here? Do we even need these permalinks?

***
I'm a bit late to the party here so there may very well be reasons for all these things I'm unaware of. 
If so, lets update the readme so we can get the site compiling :+1: