Added "iosVersion" setting, for selecting which version of iOS SDK to use.

I have iOS 7 as well as 6 installed on my machine. One of my module libraries was failing to build under iOS 7 and I had no way of forcing a build against a different version of iOS.

The setting sets the "--ios-version" parameter in the Ti CLI
Updated iosVersion command

Made an error with previous addition, should be in the right place
Merge pull request #10 from coolelephant/master

Added "iosVersion" setting, for selecting which version of iOS SDK to us...