Fix __IPHONE_OS_VERSION_{MIN_REQUIRED,MAX_ALLOWED} mixup in SSWebViewController

Signed-off-by: Alexsander Akers <a2@pandamonia.us>
Merge pull request #173 from a2/master

Fix __IPHONE_OS_VERSION_{MIN_REQUIRED,MAX_ALLOWED} mixup in SSWebViewController
Eliminate duplicate present / dismiss messages when handling modal view controllers.
Merge pull request #173 and commit 7109505911
NSDate methods for 'seconds in period' refactored