Update 'Tour' Modules + Add Central Tour

[mikhael28]

We want to have user's get a quick tour of the functionality across the entire application, as well as functionality within a specific module. We are currently using the reactour module to point out individual 'how-to-use' for a specific page. We need to rework the:

• Arena
• Sprint
• Learning
• Context

Additionally, we want to create a high level 'Tour' that someone accessing the app for the first time can use. It should be accessible from the side-navigation menu, and it should essentially be a carousel of GIF's with explainers. Those GIF's can be repurposed/drawn from the central README.