Moving message and alert prepends out of super-login.js

Placing the error messaging into the login form block with JS prepends is suboptimal. I think this should be an option rather than a standard.
Attached are screenshots showing what the messages look like in the form and when the prepends are commented out. Attached is a patch only to remove the offending lines of code, so we can use it as a patch reference. Further discussion is most welcome!