faft: Fix lint warning

This includes:
  - String format arguments as logging function paramters
  - Unused loop counter
  - Long line
  - Unused import
  - Disable W0702 when we want to catch any exception

BUG=chromium-os:35902
TEST=Run faft suite and passed.

Change-Id: I8442fefc5d0687dfe18c3563b5befbff750ba3a7
Signed-off-by: Vic Yang <victoryang@chromium.org>
Reviewed-on: https://gerrit.chromium.org/gerrit/36998
22 files changed