Travis CI for building NPM package.

As I mentioned in #2, I think we should use TravisCI for publishing this NPM package.

Here is an example `.travis.yml` configuration:

``` yaml
language: node_js
node_js:
- 0.8.0
before_deploy:
- npm run build
deploy:
provider: npm
email:
api_key:
secure:
on:
tags: true
repo: kmalakoff/node-nuget
```

I think that should work.

Start by checking the repository's existing package configuration and build entry point referenced by `npm run build`. Add and validate the `.travis.yml` configuration so tagged builds run the build and publish the NPM package using an encrypted API key; done means the Travis configuration is present and supports tagged publishing.

Written by the indexing model from the issue text.