Loading indicator when syncing

[Shrimpstronaut]

When using the 'Sync to Wordpress' or 'Sync to AD' feature, a user has no indication on the current status.

Possible solution:

• user clicks on 'Sync to ...'
• button changes state (disabled) and text ('Loading...')
• display a notification or hint ('Syncing users might take a while, depending on the amount of users')