Interrapt G26

When create new attendee phone number should be minimum 5 and maximum 15 characters in length

Steps to reproduce:
1. Click on "Attendees" section
2. Click on "Create" button
3. Enter name
4. Enter surname
5. Enter e mail
6. Enter phone number with 1 characters

Expected result: Attendee should not be created
Actual result: Message "Attendee has been created successfully" is displayed in the right corner