User settings

This is a pull request for issues #455 and #456.

You can do the workaround I am using for sending stacktraces:  https://github.com/peerlibrary/peerlibrary/blob/development/server/lib/lib/method.coffee#L10

Send as details something like: "Field:\n#{ field }" and then you on the the client [parse it out](https://github.com/peerlibrary/peerlibrary/blob/development/client/lib/notifications.coffee#L54). In this way error data is user-friendly if we do not catch it (it is still displayed in the error), but we can reuse it for special processing. I am not completely satisfied with this solution (what about localization), but I think we could us this for now.

I also later on discovered that Meteor itself is not consistent and also use another approach for extending exceptions:

https://github.com/meteor/meteor/blob/devel/packages/accounts-base/accounts_common.js#L139