Added arena endpoint to rulings

scrython/rulings/arena.py

@@ -0,0 +1,27 @@
+from .rulings_object import RulingsObject
+
+class Arena(RulingsObject):
+    """
+    cards/mtgo/:id/rulings
+
+    Gets the ruling of a card by the Arena Id.
+
+    Positional arguments:
+        id : str ................. The arena id of the card you want rulings for.
+
+    Optional arguments:
+        All arguments inherited from RulingsObject
+
+    Attributes:
+        All attributes inherited from RulingsObject
+
+    Example usage:
+        >>> rule = scrython.rulings.Arena(id='66975')
+        >>> rule.data_length()
+    """
+    def __init__(self, **kwargs):
+        if kwargs.get('id') is None:
+            raise TypeError('No id provided to search by')
+
+        self.url = 'cards/arena/{}/rulings?'.format(str(kwargs.get('id')))
+        super(Arena, self).__init__(self.url)