Enable pep8 code style checking

This patch enables pep8 code style checking. It can be invoked by running
"make check-local". This patch also finishes the pep8 clean of file
config.py.in. Once we make a file pep8 clean, we need add it to the whitelist.

Signed-off-by: Mark Wu <wudxw@linux.vnet.ibm.com>
pep8 cleanup for asynctask.py

This patch cleans up pep8 style issue in asynctask.py

Signed-off-by: Mark Wu <wudxw@linux.vnet.ibm.com>