* Centralize the error message text shown to the user in the event of a problem
installing the update in AppInfo::updateErrorMessage() and add a section
suggesting that the user should download a new copy from mendeley.com
The current update dialogs do not support retry/cancel - if a file
cannot be installed the update will just fail with an error and
any partial install will be reverted.
In the event of a failed update, display the details in a message
box and allow the user to restart the old application once the
update has been reverted.
Details of the problem will also be written to the log file.
This prevents the user closing the dialog whilst the update is in
progress. Once the update has been installed, the user can click
the 'Finish' button to close the dialog and restart the application.
