Add a preloader (waiting animation) for the time email threads are retrieved/deleted

[yanpelov]

I would add a progress bar/percentage of load progress, as you can estimate the wait time if you first do getProfile
to get the total number of emails.
For example:
getEmailProfile => 10k emails
10k means batches
say the limiter is set to 1sec between each batch
it should take at least 100 seconds to get the topTable
you can update the progress, based on this estimate
another accurate option:
you can count the batch request and update the preloader animation accordingly