Update history attributes for time according to new CESM standards

[ekluzek]

CESM updated the standards for output history files. And mizuRoute needs to update to the new standards.

This is applying the changes that are needed for CTSM to mizuRoute...

ESCOMP/CTSM#1693

mizuRoute current output:

	float time(time) ;
		time:long_name = "time" ;
		time:units = "days since YYYY-MM-DD HH:MM:SS" ;
		time:calendar = "noleap" ;

mizuroute proposed output (Changes made: time changed to type double, add new time_bounds added to give the time bounds for the averaging period.

	double time(time) ;
		time:long_name = "time" ;
		time:units = "days since YYYY-MM-DD HH:MM:SS" ;
		time:calendar = "noleap" ;
		time:bounds = "time_bounds" ;
	double time_bounds(time, nbnd) ;
		time_bounds:long_name = "time interval endpoints" ;
		time_bounds:units = "days since YYYY-MM-DD HH:MM:SS" ;
		time_bounds:calendar = "noleap" ;