Make app name settable #292

Turns out this was ever easier than I thought it would be. The `prototype.name` function already took a name parameter, but for some reason didn't allow setting?

With this alteration you can now set the name of your command very much like you would the description.

```
program = require('commander')

program
  .name('nice-cli-name')
  .description('your standard app')
```