API: All the usefull symbols in the __init__

This is necessary for easily embedding joblib in other packages while
keeping the an optional other import path

joblib/__init__.py

@@ -103,5 +103,5 @@
 from .logger import PrintTime, Logger
 from .hashing import hash
 from .numpy_pickle import dump, load
-from .parallel import Parallel, delayed
+from .parallel import Parallel, delayed, cpu_count