Makes cjs_amd work with relative path deps

This makes the cjs_amd path work with relative path dependencies. In
order to do this we needed to add esprima parsing so that we could
replace `require` calls with the normalizeMapped value.

```js
require('./a');
```

becomes

```js
require('a');
```
Merge pull request #6 from matthewp/cjsamd-relative

Makes cjs_amd work with relative path deps