Added ground-motion type of each asset to the result file
As of now, each asset in the result file has a ground-motion value; But its type is not shown in the result file (It can be of any type that is available in the ground-motion-field file). It can later be of use to know of what type the ground-motion value of an asset is.
The ground-motion type of each asset is added to the taxonomy_to_fragility() in losslib.py and later added to the damage results through the damagecalculator.py.
Closes #35 (closed)