Add validation

[matsfinsas]

• Name must be a Norwegian full name (A-Å, a-å, space)
• Validate email
• Space alone/empty is not an acceptable input on any field
• Account number must be 11 integers Add IBAN support #27
• Total size of all attachments must be below 25 MB due to limits in gmail

[matsfinsas]

Email should also be validated frontend. Invalid email gives cryptic feedback for users.

<HttpError 400 when requesting https://gmail.googleapis.com/gmail/v1/users/me/messages/send?alt=json returned "Invalid To header". Details: "[{'message': 'Invalid To header', 'domain': 'global', 'reason': 'invalidArgument'}]">

[flashedk]

proposed two pull requests to solve this