Improve error handling in plug-in auto-installation wizard
Error information while installing one or more plug-ins with the auto-installation wizard is shown for about a millisecond and are not very descriptive. The error message is basically just:
Could not install: <plug-in> in jar: <file>
and nothing more. Nothing is writted to the log. The first problem is that the dialog with error message is automatically closed as soon as the page has finished loaded. The second problem is that the error message doesn't contain any information about the real error.