install: undefined method `new' for Octokit:Module (NoMethodError)

Trying to run `rails g party_foul:install` on a new project failed with the following error after accepting my credentials and repo details:

```
...octokit-2.3.1/lib/octokit.rb:26:in `method_missing': undefined method `new' for Octokit:Module (NoMethodError)
	from party_foul-1.4.0/lib/generators/party_foul/install_generator.rb:17:in `create_initializer_file'
```

Looks like you made a typo when switching to Octokit. This pull fixes it. Thanks!