Add index.js file that returns the dist location when require()d

Add index.js file that returns the dist location and version when required:
```
var swaggerui = require('swagger-ui');
console.log(swaggerui);
```
```
{
  version: '2.0.12',
  dist: '/Users/winklerp/Documents/Projects/swagger-ui/dist'
}
```
This can then be used in a server route, e.g.:
```
server.route({
    method: 'GET',
    path: '/api-docs/{param*}',
    handler: {
        directory: {
            path: swaggerui.dist
        }
    }
});
```