Remove Refactoring notes from feature/cleanup and address PR comments

[IAmThePan]

• Have you followed the guidelines in CONTRIBUTING.md?
• Have you checked to ensure there aren't other open Pull Requests for the same update/change?
• Have you added an explanation of what your changes do?
• Does your submission pass tests?
• Did you lint your code prior to submission?

I removed all the notes I made when refactoring UNSAFE_ lifecycle events.
@christophertino Did you want to remove linting rules that are now set to 0 from .eslintrc.js?

[wlycdgr]

LGTM so far. This obviates my comments re: these in the original linting PR. Will review the other changes.

[IAmThePan]

I tried restoring IAmThePan:feature/cleanup to put these changes where they could be tracked by the original PR but it didn't track so I created this PR first to remove the Refactoring Notes then to address all the comments from the original PR.

[wlycdgr]

Looks good so far. Will review again once the last batch of comments from the original PR has been addressed (files from app/panel/reducers/panel.js onward to the end)

[IAmThePan]

I addressed all the outstanding comments on the Code Cleanup PR. Please review.

[wlycdgr]

LGTM! Thank you for fixing the banner bug along the way!