Merge pull request #142 from corliss/dev2

Some work on the Android platform (yay!)
Mac: determine scrollable border size by type, calculating doesn't work when size isn't calculated yet
cleanup
iOS: Scrollable now automatically sets edge insets for ios7
iOS: Handlers now create & keep a reference to the UIViewController created, instead of creating one every time. Fixes #117
iOS: Cleanup
Add Navigation/Splitter.IsSupported() vs using non-generator specific Supported property
Cleanup DynamicLayout code, optimize constructor passing in existing rows
Mac: Work around Dispose() bug in monomac/xammac
Mac: Minor code cleanup
Cleanup
Android: Implement Hello World app!
Add ability to easily attach to a running application for each platform using new Application().Attach(). Fixes #141
iOS: Fix compile error