Prevent clicking away during operations that take time

[tcql]

Currently, you can click away to another page while versions are downloading, or when a project is being created for the first time (waiting for files to be copied).
There are a few options:

• Show progress persistently at the bottom bar, and background the long running operation
• Prevent buttons from doing anything during long running operations
• Hide the menu during those operations

[tcql]

This is mostly handled by #2. Still need to do something for project creation, though.