GUI: Welcome Splash + Wizard

[Elv13]

This issue tracks the feature and tests done in the last month

• [X] Show a welcome splash and follow up Wizard page
  • [X] Always show the Welcome splash when client is started
  • [X] On first run / no account continue with the Wizard page
  • [X] Never show the wizard page if skip was pressed or an account has been found
• [X] Have an "import account" page
  • [X] Enter a PIN
  • [X] Enter a password
  • [X] Import the account
  • [x] Display a message if it fails
• [X] Create a new registered Ring account
  • [X] Have a "register usename" checkbox
  • [X] Have a password
    • [X] A confirmation field
    • [X] Check if they match in real time
    • [X] Block the next button if they don't
  • [X] Add an username field
    • [X] Default to the login user
    • [X] Check if it's registered in real time
    • [X] Block the next button if it isn't available
    • [X] Show an error message when the name registration failed
  • [X] Implement a timeout to avoid getting stuck

Future features

• [ ] Anonymous Ring account
• [ ] Local network account / IP to IP calls / DNS based network
• [ ] New SIP accounts / landline phone call support
• [ ] Profile page
  • [ ] Take a selfie using the camera
  • [ ] Fill random vCard fields