Add QRCode model

[michaelbag]

QRCode model should be with next fields:

• guid - unique primary key (online generator: https://www.guidgenerator.com)
• code - integration field
• name - friendly name of QR code, blank possible
• title - text information for printing on the sticker
• active (or may be archive) - it's clear i think ;)
• short_key - it's something RFC 7515 (https://en.wikipedia.org/wiki/Base64) represent of guid for encapsulation it into URL of QR code
• qr_type - template of QR code with protocol (http, https or other), root hostname for generate full URL

[michaelbag]

QR Type model fields:

• code = models.CharField(max_length=9, blank=True)
• name = models.CharField(max_length=32, blank=True)
• delete_mark = models.BooleanField(default=False)
• url_root = models.URLField()
• archive = models.BooleanField(default=False)
• fixed = models.BooleanField(default=False)

QR Code Model fields:

• created_at = models.DateTimeField(auto_now_add=True, editable=False)
• title = models.CharField(max_length=150, blank=True)
• archive = models.BooleanField(default=False)
• qr_type = models.ForeignKey(QRType, on_delete=models.CASCADE)
• fixed = models.BooleanField(default=False)

[michaelbag]

Models and Serializers - done.