Show orphans sponsorship status

https://osraav.atlassian.net/browse/OSRA-177

- add fields for sponsorship status & current sponsor (if present) to orphan show view
- add disabled sponsorship status field to orphan edit view
- create 2 new sponsorship-related methods in the Orphan model
- make step definition for 'Unable to change field' more versatile at the cost of complexity & brittleness - worth it?

OSRA-177 #Code-Review
Sorry about the string confusion, not sure what I was thinking - certainly wan't following the code properly.

As for the if's I disagree. Our coding style should be consistent and given that there has been a consistent push to shorten if - then - elses to ternaries where possible we shouldn't be making simple if statements cover three lines. 
Or vice versa I don't mind which way around it is so long as it is consistent.