Branch restriction lookup field is not case sensitive. (BB-15398)

This causes issues if there are similar usernames in the Bitbucket DB that have case differences. Such as thegarius, and TheGarius. The search field will automatically default to one of the choices, but you cannot choose which one. If the wrong user is defaulted to, then you will receive the following error:
{"error":

{"message": "write or admin access required: user_name"}

}