Campaign-Campaign Creation error message

[jinhakang]

Error message from previous trial of creating campaigns stays there even when I click 'Create Campaign' again and also when the error is not valid any more. The error message here means the one embedded on the page not the pop-up one.
Once I get the error message, then the error message also appears on the already create campaign's edit page.

Error message:
Campaign could not be saved. »hide
Campaign must belong to at least one class.

[shlurbee]

made it a dialog for now:
3bab8d3

pushed to mdev1