add Package SQLAlchemy ORM model

Additionally, add an optional **kwargs passing via make_relationship.
This allows us to use things like `uselist=False`, which was needed
for test/test_package.py.

Signed-off-by: Kevin Morris <kevr@0cost.org>

aurweb/models/package.py

@@ -0,0 +1,24 @@
+from sqlalchemy.orm import mapper
+
+from aurweb.db import make_relationship
+from aurweb.models.package_base import PackageBase
+from aurweb.schema import Packages
+
+
+class Package:
+    def __init__(self,
+                 PackageBase: PackageBase = None,
+                 Name: str = None, Version: str = None,
+                 Description: str = None, URL: str = None):
+        self.PackageBase = PackageBase
+        self.Name = Name
+        self.Version = Version
+        self.Description = Description
+        self.URL = URL
+
+
+mapper(Package, Packages, properties={
+    "PackageBase": make_relationship(PackageBase,
+                                     Packages.c.PackageBaseID,
+                                     "package", uselist=False)
+})