added bolean request_fulfilled field to sponsor model

OSRA-88 #code-review #comment explicitly return true on before_create method
to ensure record saved
added request_fulfilled field into the views

-shown in index, show and edit
-not shown in create
-ensures field is true or false
-set field before create

OSRA-87 OSRA89 OSRA-90 #code-review
added constraints to request_fulfilled field

https://osraav.atlassian.net/browse/OSRA-87
OSRA-87 OSRA-88 #code-review
- added not null constraint because this field must be true or false
- added index as this field will be searched on as part of the story