We have intentionally left this open-ended, since we wanted the skills to be defined by the applications themselves. Since the services we're bringing to bear to enhance the scientific application are "web" services, and mostly expose REST APIs, we used this as the common denominator. However, the participants are free to determine which services and tools are important for them.
Since we expect that outcomes of the school would be web-facing science gateways, which may need some kind of content management system, typically we would expect the users to know how to work with one of these - Liferay, Joomla, Plone, Drupal, Wordpress, etc. However, the gateway can also be a messaging system like Slack, or a desktop application.
We will be working with the team to plug their workflows and applications into infrastructure services where it makes sense (we will help them to identify this), so as to improve their collaboration and research outputs.