Ability to customize travis status messages

We’d like to be able to customize the status message that is returned from a build. It would be extremely useful to be able to include additional information in the message, like test failure counts, or links to artifacts we uploaded somewhere.

We can do something like this with the github api ourselves, but it requires that we expose a github token to the build which is awkward and prevents us from using it on builds from forks. A built in command available that doesn’t require us to expose a token would be useful.

I imagine it could be something like:

- set_custom_status "There were ${failures} test failures, please see the test log at ${log_location}"

A general ability to comment on the associated PR from a build would be useful as well.