Framework cleanup

[scotthavens]

First pass at cleaning up the AWSM class. The __init__ was quite large, grouped like commands for parsing the config file.

• removed the wyhr option for the output folders, start_end will be the default
• updated config options proj to project_name and desc to project_description #56
• use SMRF Topo class for reading the topo instead of spatialnc
• use xarray to select the closest time if initializing from a previous snow.nc file
• cleaned up the logger a bit
• added timezone information to the start and end dates
• Fix issue #64 to make the model change netcdf have nan values where there was no update