Adds sample app and Runners sections

Adds many slides for configuration options and a slide for Runners

content/docker.md

+## Docker
+
+Download and modify a Docker image:
+
+```
+docker images
+docker run -t -i ruby:2.3 /bin/bash
+
+$ apt-get update
+$ apt-get install nodejs -y
+$ gem install bundler --no-ri --no-rdoc
+# A Dockerfile is a great option for the following line or
+# maybe integrate with our current CI script?
+$ bundle install
+$ exit
+
+# Log back in?
+docker ps -a # and get container sha
+docker start -i <container-sha>
+```
+
+----------
+## Create a custom image
+
+```
+# Commit a new image
+docker commit -m "Adds dependencies" -a "Peter Parker" \
+<container-sha> registry.gitlab.com/<group-name>/projectname:v2
+
+# Or commit the image and tag it later
+docker tag <image id> <url>:<port>/<user/project>:<tag>
+
+# Login in to GitLab registry
+# docker login registry.gitlab.com
+docker login <url>:<port>
+
+# Push image to registry
+# docker push registry.gitlab.com/gitlab-org/ci-training-sample
+docker push <registry-url>/<group-name>/<project-name>:<tag>
+```
+
+[Back](#/agenda)