Begin incorporating Python unit tests into build

We now build a separate APE binary for each test so they can run in
parallel. We've got 148 tests running fast and stable so far.

third_party/python/Lib/json/scanner.py

@@ -5,6 +5,8 @@ try:
     from _json import make_scanner as c_make_scanner
 except ImportError:
     c_make_scanner = None
+if __name__ == 'PYOBJ.COM':
+    import _json
 
 __all__ = ['make_scanner']