fix setup.py SDKVERSION
fix setup.py SDKVERSION

baidubce/__init__.py import non built packages though util.py
which will cause python setup.py install (or any other subcommand)
error. Fixed by reading SDKVERSION by parsing file instead of
import.

Change-Id: Ief2f6a2ede37b3e0a166eabe71cee43835efdce8

baidubce/bce-sdk-python,baidubce/bce-sdk-python