#621: UIStepperView fixes

@dhanya : code review is complete. Looks good except one minor issue:
To make our code more simpler and easier to maintain, and also given that long long is good enough in most cases, let's just use long long and [NSNumber numberWithLongLong]. So for all the commented lines, use long long and numberWithLongLong instead.

Btw, I've noticed this pull request contains commits pulled from master branch. Master branch is actually not an active branch. Bob is mainly working on develop branch for android and server changes, and for iOS we should only work on ios-init branch, cut new branch from it and pull commits from it to your local branch. 

So after you've finished the final fix, I suggest you cut a new branch based on the latest ios-init, and then copy-paste your code to the new branch and send a new pull request.