Fix and update gitlab

[midiland]

Hello,
After several attempts I could not get the code to work with gitlab,
I finally :
I changed the gitlab lib for the last version : https://www.npmjs.com/package/@gitbeaker/node
I updated the tests.

With the modifications I can create a push branch and make a MR

[smalltimer]

Hi guys, I'm not sure if this is the place for me to comment, but I can't get staticman to work with gitlab either. I have two main problems afaict:

1. While I get the welcome to staticman at {STATICMAN_BASE_URL} , I get a GET error when trying to access {STATICMAN_BASE_URL}/api-docs . This makes me wonder if I the heroku app has a problem.

2. I'm working on a gatsbyjs site with Formik. My comments repo is hosted in a gitlab group (an awesome gitlab feature which lets me group related projects together) and I have no idea how to target this repo in my Formik fetch requests.

[alexwaibel]

Looks great, thanks for submitting this. Could you please resolve the merge conflicts and then I'd be happy to merge it.

[rriemann]

Thank you so much for this effort. I hope it can be merged soon! I also struggle with making it work with gitlab.