Restrict branches to run Travis.

[junaruga]

Summary

Restrict branches to run Travis.

Details

For example, below case.
2 builds (PR and branch push) on Travis are running.
#465

When sending pull-request from cucumber/aruba repository's branch,
prevent 2 builds to run.

Motivation and Context

Saving the resource.
That affects Travis's running time.
If the time becomes shorten, contributors are happy.

How Has This Been Tested?

When sending pull-request from cucumber/aruba's branch, that is tested.

Screenshots (if appropriate):

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Refactoring (cleanup of codebase withouth changing any existing functionality)
• Update documentation

Checklist:

• I've added tests for my code
• My change requires a change to the documentation.
• I have updated the documentation accordingly.

[aslakhellesoy]

Hi @junaruga,

Thanks for your making your first contribution to Cucumber, and welcome to the Cucumber committers team! You can now push directly to this repo and all other repos under the cucumber organization! 🍾

In return for we ask you to:

• ✅ Please continue to use branches and pull requests. When someone on the core team approves a pull request (yours or someone else's), you're welcome to merge it yourself.
• 💚 Commit to setting a good example by following and upholding our code of conduct in your interactions with other collaborators and users.
• 💬 Join the community Slack channel to meet the rest of the team and make yourself at home.
• ℹ️ Don't feel obliged to help, just do what you can if you have the time and the energy.
• 🙋 Ask if you need anything. We're looking for feedback about how to make the project more welcoming, so please tell us!

On behalf of the Cucumber core team,
Aslak Hellesøy
Creator of Cucumber