Add tests for get_dict.

biscuit/core/tests/test_data_helpers.py

+from biscuit.core.templatetags.data_helpers import get_dict
+
+def test_get_dict_object():
+    class _Foo(object):
+        bar = 12
+
+    assert _Foo.bar == get_dict(_Foo, 'bar')
+
+def test_get_dict_dict():
+    _foo = {'bar': 12}
+
+    assert _foo['bar'] == get_dict(_foo, 'bar')
+
+def test_get_dict_list():
+    _foo = [10, 11, 12]
+
+    assert _foo[2] == get_dict(_foo, 2)
+
+def test_get_dict_invalid():
+    _foo = 12
+
+    assert get_dict(_foo, 'bar') is None