Why so complicated? As a first step Please give me a Deployments Page that gives me the option to run simples SH Scripts in the Runner on click, parameterised please. All I need is a nice GUI for my QA people that allows them to deploy(which for our PHP site basically just means copy and DB Import) Branch x on Server y.
Jenkins is total Overkill for that but GitLab CI doesnt leave me with enough GUI to skip it either.
If you want to securely store login credentials consider using secure variables http://doc.gitlab.com/ce/ci/variables/README.html