Make starter work with Deno 1.0

[keyvez]

• Use importmap.json to correctly import unversioned imports in std (this was breaking due to 'v' prefix)
• Upgrade dotenv to 0.4.3 to fix a dep error
• Upgrade mysql to 2.6.1 to fix a dep error
• Upgrade bcrypt to 0.2.3 to fix a dep error
• Upgrade djwt to 1.0 to fix a dep error
• Migrate usage of validateJwt to 1.0
• Update README

[keyvez]

Let me know what you think about it.