perf-info.py: Fix pyflakes and pep-8 warnings

Signed-off-by: Stéphane Graber <stgraber@ubuntu.com>
nettop.py: Fix pyflakes and pep-8 warnings

Signed-off-by: Stéphane Graber <stgraber@ubuntu.com>
iotop.py: Fix pyflakes and pep-8 warnings

Signed-off-by: Stéphane Graber <stgraber@ubuntu.com>
fd-info.py: Fix pyflakes and pep-8 warnings

Signed-off-by: Stéphane Graber <stgraber@ubuntu.com>
ctf-filter.py: Fix pyflakes and pep-8 warnings

Signed-off-by: Stéphane Graber <stgraber@ubuntu.com>
cputop.py: Fix pyflakes and pep-8 warnings

Signed-off-by: Stéphane Graber <stgraber@ubuntu.com>
Merge pull request #6 from stgraber/master

Some more pyflakes and pep-8 fixes