Soil Update

Fixed some errors in the soil reflectivity. Also added a direct version
of memls that takes the snow inputs as a 1 layer vector rather than a
text file.
[WIP]
* Added directory to input for churchill
* Added R file to process churchill pit data to MEMLS input format
Merge branch 'AK_snowdrift'

* AK_snowdrift:
  [WIP] * Added directory to input for churchill * Added R file to process churchill pit data to MEMLS input format
  Soil Update