Merge branch 'soil_moisture' into 'master'

Soil moisture

I added the soil moisture variable in the list of variables issue number #12 I also took the opportunity to remover the monthly_nbday scripts which are outdated.
I add the file table_of_variable and template.nc into the git repository because I though that it was better to have everything together and safer to have it version controlled. I also modify the default config file to go with this change.
I solved also issue #13 and #11.

I tested it with m04o and it seems to works well. I will test it also with m04r, m04p, m04s. I don't know if some one else could test it.

People potentially interested ( @eexarchou @obellprat @mmenegoz )

See merge request !5