Coupler history files do not restart properly

[billsacks]

The coupler's average (rather than instantaneous) and auxiliary history files do not restart properly. This is a problem for #873 , but is also a more general problem, such as for data assimilation runs that have frequent restarts.

Currently, no attempt is made to save accumulating cpl fields to a restart history file.

[rljacob]

Discussion on telecon: any averaged file where the restart is in between history writes won't work. Code to save intermediate average isn't in the mct coupler.

[billsacks]

@mvertens is this an issue for CMEPS, too - that cpl avg hist files won't restart properly? If so, I'll move this issue there; if this works, though, I'll close it.

[mvertens]

@billsacks - yes this is an issue for CMEPS that should be assigned to me.

[billsacks]

Moved to ESCOMP/CMEPS#253