Improve handling of logs to follow for LogEntries

[eybot]

Here is an idea to make the ey-logentries recipe way more user-friendly.

Right now, we're stuck with hardcoded log paths, which is a pain for users who want to track custom logs.

What if we set up an environment variable called EY_LOGENTRIES_FOLLOW_PATHS? It'd work just like the EY_PACKAGES variable. This way, users could easily add their own log paths without having to mess with the recipe itself. Keep all the default logs that are already being tracked, but users could add in their own app-specific logs too.