cli.py: reorder imports: pkg_resources before argparse

Related warning from pychecker:
 ceph_deploy/cli.py:3: UserWarning: Module argparse was already
 imported from /usr/lib64/python2.7/argparse.pyc, but
 /usr/lib/python2.7/site-packages is being added to sys.path
 import pkg_resources

Signed-off-by: Danny Al-Gaaf <danny.al-gaaf@bisect.de>
admin.py: remove unused, but imported modules

Signed-off-by: Danny Al-Gaaf <danny.al-gaaf@bisect.de>
config.py: remove unused, but imported modules

Signed-off-by: Danny Al-Gaaf <danny.al-gaaf@bisect.de>
discover.py: remove unused, but imported modules

Signed-off-by: Danny Al-Gaaf <danny.al-gaaf@bisect.de>
forgetkeys.py: remove unused, but imported modules

Remove unused modules os.path and exc. Import os module in forgetkeys()

Signed-off-by: Danny Al-Gaaf <danny.al-gaaf@bisect.de>
gatherkeys.py: remove unused, but imported module exc

Signed-off-by: Danny Al-Gaaf <danny.al-gaaf@bisect.de>
mds.py: remove unused local variable/import

Signed-off-by: Danny Al-Gaaf <danny.al-gaaf@bisect.de>
osd.py: add missing imports

Signed-off-by: Danny Al-Gaaf <danny.al-gaaf@bisect.de>
zapdisk.py: remove unused local variable

Signed-off-by: Danny Al-Gaaf <danny.al-gaaf@bisect.de>
Merge pull request #4 from dalgaaf/wip-da-pychecker

Some small fixes

Reviewed-by: Sage Weil <sage@inktank.com>