Changed wkwebview-engine doc to reflect expectations of completeness of the plugin.
Update README.md
Updated Plugin to iOS 8 (closes #16)

Apple changed the way Keyboard Views are created and plugins was
crashing the App;

Signed-off-by: Shazron Abdullah <shazron@apache.org>
Implemented /local-filesystem/ and /asset-library/ handlers.
Rolled in GCDWebServer+LocalhostOnlyBaseHandler Obj-C category into main class, so it will use the common code for all the handlers.