fix(serialize): add true as an accepted value for bool

[stiefeljackal]

When I was working on getUsersFollowingMe, I noticed that shouldMapToBooleans was not properly mapping true or false when the API responds with those values. This bug remained undetected since almost all responses from RA's API return either a "1" or "0" for a Boolean field. Since API_GetUsersIFollow.php and API_GetUsersFollowingMe.php return either true or false for their Boolean fields, the serializer function will always map the value as false due to the missing check for true. This PR fixes this issue by adding a check for the stringified version of true.

[wescopeland]

Thanks!