Optional attributes with Defautls

[emjunior258]

The following attributes must be optional when creating issuers and certificates via the API:

• geographic address
• key strength
• path length
• validity

The API must provide endpoints to set and get default values which will be used by the backend for this attributes:

• GET /defaults
• PUT /defaults

The default values must be stored under defaults.json in the data directory. The defaults.json file must be created on startup if it doesn't exist and it's contents MUST be the following:

"geographic_address": {
    "country": "MZ",
    "state": "Maputo",
    "locality": "Kampfumo",
    "street_address": "AV. 25 de Setembro, Rua dos desportistas, Nr 001"
},
"key_strength": "HIGH",
"path_length": 5,
"validity_days": 365