add aurweb.models.user.User

+ Added aurweb.models.user.User class. This is the first example
  of an sqlalchemy ORM model. We can search for users via for example:
  `session.query(User).filter(User.ID==1).first()`, where `session` is
  a configured `aurweb.db.session` object.
+ Along with the User class, defined the AccountType class.
  Each User maintains a relationship to its AccountType via User.AccountType.
+ Added AccountType.users backref.

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

test/test_user.py

@@ -0,0 +1,52 @@
+import pytest
+
+from aurweb.models.account_type import AccountType
+from aurweb.models.user import User
+from aurweb.testing import setup_test_db
+
+
+@pytest.fixture(autouse=True)
+def setup():
+    setup_test_db("Users")
+
+
+def test_user():
+    """ Test creating a user and reading its columns. """
+    from aurweb.db import session
+
+    # First, grab our target AccountType.
+    account_type = session.query(AccountType).filter(
+        AccountType.AccountType == "User").first()
+
+    user = User(
+        AccountType=account_type,
+        RealName="Test User", Username="test",
+        Email="test@example.org", Passwd="abcd",
+        IRCNick="tester",
+        Salt="efgh", ResetKey="blahblah")
+    session.add(user)
+    session.commit()
+
+    assert user in account_type.users
+
+    # Make sure the user was created and given an ID.
+    assert bool(user.ID)
+
+    # Search for the user via query API.
+    result = session.query(User).filter(User.ID == user.ID).first()
+
+    # Compare the result and our original user.
+    assert result.ID == user.ID
+    assert result.AccountType.ID == user.AccountType.ID
+    assert result.Username == user.Username
+    assert result.Email == user.Email
+
+    # Ensure we've got the correct account type.
+    assert user.AccountType.ID == account_type.ID
+    assert user.AccountType.AccountType == account_type.AccountType
+
+    # Test out user string functions.
+    assert repr(user) == f"<User(ID='{user.ID}', " + \
+        "AccountType='User', Username='test')>"
+
+    session.delete(user)