Complete error handling

* Include error circumstance in logo showing
* Include handling of blank surveys
* Otherwise touch up and improve error handling
Add errors partial
Fix redirect for survey update

* Redirect to confirmation page if successful
* Re-render edit if unsuccessful
Replace email with username

* No reason to enter an email, so usernames are better
* Replace all instances of email with username
Add landing page with recommended surveys

* Add landing page so new users can take surveys
* Create boolean recommended column
* Show recommended surveys on landing page