Wrong timestamps in reports.

[TYZzzzzzz]

Describe the bug
In reports timestamps save with unknown time zone, testcase was run at 17:03 localtime, record in report file:
" ...
finished: '2018-11-12 12:05:20'
started: '2018-11-12 12:03:05'
... "

To Reproduce
Steps to reproduce the behavior:

1. Run and finish testcase
2. Open report
3. See 'started' and 'finished' timestamps

Expected behavior
Saving timestamps in local time of OS.

System (please complete the following information):

• OS: Windows 7 Professional Service Pack 1
• Python 3.7
• Version 0.4.1

Additional note
Expecting "started-finished" sequence if report files intended to human reading