Gandi Simple Hosting is a website that is really nice for people who don't want to update themselves tools like MySQL, PHP versions, etc... on their remote. I'm one of them and I really like the easy way provided by Gandi to host web pages for a reasonnable price.
But, as you don't control everything that is installed on the server, there is sometimes limitations. I will try to overpass them and give some tips when i encountered them.
Jekyll Configuration
If you want to use Jekyll static pages, do the following in config.yml:
source: "./_source"
destination: "./htdocs"
And then build locally your website and push everything in the remote. All your source files you can change will be in /_source and the static html pages will be in /htdocs.
That way, you keep all files in git and can push everything in gandi remote.
To deploy you can use traditionnal ssh {login}@git.{datacenter_location}.gpaas.net 'deploy {vhost}.git to deploy