Remove strip_attributes

* It's been causing all manor of issues with the Rails upgrade. These have been fixed but it points to this being a britle part of the application
* Presumably it was added to Alaveteli to make the data tidier. This hasn't really helped in real world installations as the data is kinda messy but that's OK. Stripping leading/trailing whitespace is hardly the leading cause of untidy data for us

Unless there's a good reason to keep this I say we remove it.