It's just a crappy spelling of Austin. Let's not change spellings people, I really hate that. That's how my name has ended up being spelled a million different ways (ex: Joni, Jonni, Jonnie, Joani).
I don't quite get the supposed ''feminizing'' effect of shoving a 'y' to the slot of the unstressed vowel either. The name is still pronounced exactly the same, it is still masculine, and it doesn't sound cool on an adult woman. The manly/boyish names on a girl/woman-thing may work on tomboyish and cool girls and young women, but not on women past the age of 27. Plus, this is plain bad spelling.