Stricter flake8 check

- remove some flake8 warnings from ignore list;
- enable flake8 for tools;
- fix flake8 warnings for tools.

Change-Id: I5ddb5f7a3c62be1c7f88440bdf82bd93783f46de
yyoom tool accepts new parameters --log-file and --quiet

Changed command prompt parameters for yyoom tool.
There are two new parameters:
--log-file to set path to log file
--quiet write only error information in err
yum_helper now calls execute istead of execute_save_output2

Change-Id: I4e5583a902d2243e99b34664055b5e65be83868d
Add ability to clone by SHA1

Change-Id: Ie7f131053c40c2098507ca42ac8c44961f7525b8
Merge "Add ability to clone by SHA1"
Merge "Stricter flake8 check"
Merge "yyoom tool accepts new parameters --log-file and --quiet"