Grant : Amount Requested (orig currency) and Amount Granted columns in schema should be NOT REQUIRED

Currently amount_requested and amount_granted columns have <required>true</required> in Grant.xml. However, these are not required fields on the Grant form. This results in NULL field values being saved as 0.00 which is confusing and misleading.

Modify Grant.xml to remove the required attrib for these 2 fields - and verify that saving a new grant w/ empty values results in NULL value in the DB for these columns.