Set 'period', 'duration' config parameters in seconds

Parameters 'period' and 'duration' from task config for periodic
and coninuous runners, respectively, are set in seconds, according
to docstring. However, in code they are multiplied by 60 and thus
effectively set minutes, not seconds. This change is intended to
restore the consistency of code.

bug #1285074

Change-Id: I7617f6b59d3768ee7b280c48fdf70d6d60eb3fec
Merge "Set 'period', 'duration' config parameters in seconds"