Autosave:
- Move the 'Saving post' and 'Draft saved at...' strings from autosaveL10n to postL10n as they are used only there.
- Use the custom jQuery events 'before-autosave' and 'after-autosave' to show these messages.
- Separate autosave.suspend() for local and server so local autosaves can continue while server autosaves are suspended.
- Remove the recently added autosave.server.disable() and use autosave.server.suspend() instead.
- Bring back .button.disabled, button-primary.disabled and use .disabled to prevent multiple form submissions.
See #25272.


git-svn-id: https://develop.svn.wordpress.org/trunk@27038 602fd350-edb4-49c9-b593-d223f7449a82