Fix #64 - ensure to dedupe boot scripts array before running.

Because the bootDirs defaults to process.cwd(), if the user manually
includes scripts in the same directory, with out specifying a bootDir,
those scripts will be included multiple times.

Use underscore.uniq to remove duplicate file paths.

Fix #64.
If the script is listed twice, the assertion on L417 fails and L418 is never called. When L417 passes, then there is exactly one item in the array and L418 passes too.

Try it yourself:

```
$ node
> require('chai').expect([1, 1]).to.eql([1])
AssertionError: expected [ 1, 1 ] to deeply equal [ 1 ]
```