HybridWebView left/right swipe gestures added

Android & iOS completed, needs WP8 implementation.
Added Extended Master Detail Page

On iOS this will let you choose whether the menu is visible on iPad
when in landscape mode. Default is non-visible opposite to
MasterDetailPage on Forms.

Currently there is no extended functionality for Android or WP8 but the
renderers are there so if we ever add more functionality to the page
then we have them ready.
Merge remote-tracking branch 'upstream/master'
Merge pull request #450 from sami1971/master

Extended functionality (HybridWebView & MasterDetailPage)