Pipelines onboarding to support repos with merge checks

The pipelines on-boarding takes you through a really nice process of setting up a bitbucket-pipelines.yml file. However, for a repository with restrictions on how one can merge to master (ie. a PR with approvals is required) - the on-boarding breaks. It would be nice if in the case that a commit to master is not possible, the on-boarding generates a PR with the .yml file you just created.