User information fields are not verified

[pekman]

When editing user information, ASI doesn't allow email and gender fields to be changed to empty. There should be a local verification for these values and error messages should be shown to the user, if the values are invalid.

[pekman]

Current behavior: If these fields are empty on submit, they are silently ignored and the corresponding values in ASI remain unchanged.

It might be better if empty email displayed an error message. The status of the gender field is more complicated: When creating a new user, ASI allows gender to be unspecified, but once it's been set to male or female, ASI doesn't allow it to be changed to unspecified. It might be best to just require the users to always specify their gender.

[pekman]

Email field fixed. The issue with gender field remains. As an additional complication, there is no gender field when creating a new user and adding the field requires an additional ASI request on creating new users.