Travis build does not copy JAR to S3 on Pull Request branches about analysis-backend

[abyrd]

This seems to be the reason: https://docs.travis-ci.com/user/pull-requests/#Pull-Requests-and-Security-Restrictions
Someone could submit a PR that causes Travis to print out all your secure variables. Currently encrypted variables are made available by Travis only in "safe" PRs, "as long as the origin of the pull request and the target repository are the same".

So rather than testing whether this is a PR, we should test whether the AWS credentials are defined.

[abyrd]

This leads to another problem: the $TRAVIS_BRANCH on pull requests is the branch the PR is merged into, not the branch of the PR itself. So the JAR file is often called master-X.jar instead of having the right branch name.

[ansoncfit]

We plan to switch CI providers. Closing.