Add option for idempotent messaging

[gustafnk]

In some scenarios it might be valuable to NOT add a growl message if there already exists a message with the exact same text.

For example, I have generic http error handler in a service and if something fails, I get one message for each failed http request. But I would only like to display a single growl message to the user.

This is of course specific to my application, but I think it could be valuable to others as well. Would you be interested in a pull request for this functionality?

[marcorinck]

yes, that would make sense, absolutely.

In fact, I think that should be the standard behaviour, which you should be able to turn off via $growlProvider.

If you want to send a PR please send it to development branch.

[marcorinck]

maybe you should name the option "onlyUniqueMessages" or sth. like that. While "idempotent" is technically correct, it would be easier to understand.

[gustafnk]

Yeah, that is a much friendlier name :)

[marcorinck]

I just checked in my solution to the development branch, what do you think?

[gustafnk]

Beat me to it :) I think it looks good.