[FIX] Platform version for iOS 7

I'm not 100% sure that Mobile Safari 7.0 necessarily implies iOS 7, but we're getting iOS 7 users showing up in our system as iOS 6 and I believe this is why.

Thanks


FYI @koden-km
Merge pull request #18 from jmalloc/patch-1

[FIX] Platform version for iOS 7