Force password creation on first island launch.

[VakarisZ]

Upon launching island first time, user should be prompted to choose and repeat a password. Once password is chosen, it should be saved in a hashed form and used in JWT. For now, I don't think username is required. Additional features could be:

• Verification, that password is >6 symbols long.
• Multiple passwords, so that multiple users could access island.
• Wiki entry about how to manually change password.