Complete refactor:

- Now implemented as 2 separate categories: UIScrollView+SVPullToRefresh and UIScrollView+SVInfiniteScrolling;
- The views now belong to the UIScrollView and not the other way around as it was before (fixes memory issues);
- Allow custom titles, subtitles, and views for each state (e.g. setCustomView:forState:);
- Demo now illustrates both categories;
- All the date subtitle stuff is now deprecated, use setSubtitle:forState: instead.
- The showsPullToRefresh and showsInfiniteScrolling should now completely hide the view and reset the scrollView's contentInset to its original value.
Fix formatting issue with readme.
Fix bugs with title, subtitle and custom view setters.
Fix bug with activity indicator centering (thanks @merowing_).
Add SVRootViewController and UINavigationController and three "- (void)dealloc" to show the retain cycle memory leak. And use __weak/weak to fix the bug. Also can use instruments to see the memory bug
Add enabled property to SVInfiniteScrolling (keeps the view around, but disables action handler and state changing; state will always return SVInfiniteScrollingStateStopped).
In SVPullToRefresh, the UIScrollView has add a KVO observer, but when the UIScrollView dealloc, it doesn't remove the observer. Also, it seems that the UIScrollView has no way to remove the observer elegantly without change the public api. I fix the bug with some trick, maybe not elegant, but it does can work -- I remove the observer in the "willMoveToSuperview" func of SVPullToRefreshView. ##The same bug with SVInfiniteScrolling.
within willMoveToSuperview, add a check to see whether there is a need to call removeObserver
Fix subtitles not displaying issue

The only way to display a subtitle label was to set the deprecated lastUpdatedDate property. Calling setSubtitle:forState: now always display subtitles.
Merge pull request #76 from 0xced/showsDateLabel-fix

Fix subtitles not displaying issue
Merge branch 'master' of github.com:samvermette/SVPullToRefresh
Clean up.
Don't overwrite horizontal content offset when calling startAnimating and stopAnimating.
Safer observing.
Merge pull request #81 from krzysztofzablocki/master

Better handling of key value observing.
make title & subtitle widths wider, to accommodate longer text

A subtitle string like "Last updated: 12/12/12, 12:58 PM" would
truncate with the old subtitle width
Merge pull request #82 from funkadelic/master

Update title & subtitle label widths
Expose titleLabel and subtitleLabel for custom configuration
Merge pull request #84 from krafttuc/expose-labels

Expose titleLabel and subtitleLabel for custom configuration
Fixes -Wnewline-eof error