Create plan for saving "color dot" state across `kubetail logs` instantiations

[amorey]

Our goal is to modify the default output of the kubetail logs command to look like this (see #680 for more context):

After the "color dot" identifer is implemented, we need to add a way to save state across instantiations so that the containers get assigned the same color anytime the tool is used.

Before implementing this feature we need to consider these questions:

• How should we save state (text file, sqlite)?
• How should we deal with concurrency issues?
• How should we handle schema changes on upgrade?
• How should we handle cleanup for dead containers?

After answering these questions let's determine the best way to implement the feature.