Small loading messages tweaks
Small loading messages tweaks

Summary:
This removes the Thanksgiving-ish message, and adds a couple more filler
messages.

Test Plan: None

Reviewers: guido

Reviewed By: guido

Subscribers: changesbot

Projects: #changes_ui

Differential Revision: https://tails.corp.dropbox.com/D171900

dropbox/changes,dropbox/changes,dropbox/changes,dropbox/changes