Update monkeypatch to handle list of Schema classes

[digitaldogsbody]

This updates the monkeypatcher to allow passing a list of Schema objects as well as a single one.

from ..loader import monkeypatch_schema
from ..skeleton import Manifest, Canvas

class ExampleHelper:
    def example_helper(self):
        return "First Example"

class ExampleHelper2:
    def example_helper2(self):
        return "Second example

monkeypatch_schema(Manifest, ExampleHelper)
monkeypatch_schema([Manifest, Canvas], ExampleHelper2)