We need to DRY this up. `preprocess` should use the src-dest syntax and this should ref. the dest of preprocess.

Something like this:

```js
preprocess: {
  core_build: {
    src: 'src/wreqr.js',
    dest: 'lib/backbone.wreqr.js'
  }
},

template: {
  core: {
    src: '<%= preprocess.core_build.dest %>',
    dest: '<%= preprocess.core_build.dest %>'
  }
}
```