UIActivityViewController support for iOS6+

[rileytestut]

By setting the new boolean useActivityViewController to YES, SVWebViewController will now present a UIActivityViewController instead of a UIActionSheet. SVWebViewController also now has an applicationActivities property where the programmer can pass in an array of custom UIActivities to display alongside the included ones.

For this implementation, I have included git submodules TUSafariActivity and ARChromeActivity for SVWebViewControllerAvailableActionsOpenInSafari and SVWebViewControllerAvailableActionsOpenInChrome because UIActivityViewController does not come with these activities. However, this means any person who clones your repo has to now do the extra step of updating the modules, so if you were aiming to be the easiest WebViewController to add to a product you may want to remove references to these.

[samvermette]

I really want this to work, but the 3rd party dependencies are indeed bothering. Will try to think of what's the best way to do this.

[rileytestut]

It shouldn't be too hard to reimplement them yourself, or even I could do it and send another pull request. The problem is that all UIActivities require an icon, and I certainly don't have the necessary designer skills to create my own versions.

[samvermette]

Well reinventing the wheel is a waste of time imo. I think using existing open-source activities is the way to go...

[samvermette]

Just pushed this to master.