Refactoring the code

- Use Flask blueprint
- Split model and views into smaller parts
- Bug fixes
- API adjustment

powerdnsadmin/models/base.py

@@ -0,0 +1,7 @@
+from flask_sqlalchemy import SQLAlchemy
+
+db = SQLAlchemy()
+domain_apikey = db.Table(
+    'domain_apikey',
+    db.Column('domain_id', db.Integer, db.ForeignKey('domain.id')),
+    db.Column('apikey_id', db.Integer, db.ForeignKey('apikey.id')))