Add download of openapi-generator script

[gmcculloug]

After spending some time with other travis scripts I started thinking it would be better to move the download of openapi-generator-cli to this common method instead of requiring each caller to have to download it separately as part of the .travis.yaml

It's not a big impact here (2 new lines), but the caller's .travis.yml file can be reduced to one line:

- - curl -L https://raw.githubusercontent.com/OpenAPITools/openapi-generator/master/bin/utils/openapi-generator-cli.sh
-   > ./openapi-generator-cli
- - chmod +x ./openapi-generator-cli
- - curl -L https://raw.githubusercontent.com/RedHatInsights/insights-api-common-rails/master/.travis_scripts/openapi-validator.sh
-   > ./openapi-validator.sh
- - chmod +x ./openapi-validator.sh
- - ./openapi-validator.sh
+ - curl -sSL https://raw.githubusercontent.com/gmcculloug/insights-api-common-rails/master/.travis_scripts/openapi-validator.sh | bash -s

If you like this approach it can be merged ahead of updating the callers to use the 1-line call.

[bzwei]

Shall we add an echo here to indicate the curl download is completed?

[gmcculloug]

@bzwei Added an echo. Is that what you were looking for?

[dippy-bot]

Checked commit b9a6e4e with ruby 2.5.7, rubocop 0.69.0, haml-lint 0.35.0, and yamllint
0 files checked, 0 offenses detected
Everything looks fine. ⭐

[lindgrenj6]

@gmcculloug does this need a new gem release? or is this script just downloaded from master in the child-repos?

[syncrou]

LGTM 👍

[gmcculloug]

@lindgrenj6 No, the callers pull this file directly from the master branch during the travis test run.

Example: https://github.com/RedHatInsights/sources-api/pull/244/files

[lindgrenj6]

@gmcculloug cool, LGTM then!