use_travis_deploy: Setup deployment for Travis CI
In romainfrancois/travis: Set Up 'Travis' for Testing and Deployment

Creates a public-private key pair, adds the public key to the GitHub repository via github_add_key(), and stores the private key as an encrypted environment variable in Travis CI via travis_set_var(), possibly in a different repository. The tic companion package contains facilities for installing such a key during a Travis CI build.

1 2	use_travis_deploy(path = ".", info = github_info(path), repo = github_repo(info = info), travis_repo = repo)

`path`	`[string]` The path to a GitHub-enabled Git repository (or a subdirectory thereof).
`info`	`[list]` GitHub information for the repository, by default obtained through `github_info()`.
`repo`	`[string\|numeric]` The GitHub repo slug, by default obtained through `github_repo()`. Alternatively, the Travis CI repo ID, e.g. obtained through `travis_repo_id()`.
`travis_repo`	`[string]` The Travis CI repository to add the private key to, default: `repo` (the GitHub repo to which the public deploy key is added).