Timeseries for land needs to include additional information

[TeaganKing]

Land h0 files should include additional information (area, landfrac, landmask).

This feature already exists in some timeseries generation options (sounds like from Gary Strand, Keith Oleson has been using this).

This can also be done with 'ncks -A -v area,landfrac, landmask'

@wwieder brought this up.

[nusbaume]

Just wanted to add a note here that depending on the situation atmosphere history files also need additional information. So if we can make a generalizable mechanism for bringing in "extra" variables or attributes that would be ideal. Thanks!