Touch support

[alexreardon]

Will complete #11

Still a big work in progress

• Add documentation explaining how the touch dragging works
• Add a caveat that auto scrolling is not supported yet
• Add mobile friendly links to the documentation (storybook sucks for mobile)
• fix flow
• Update docs with new flow types
• Update docs
• Add native scroll direction diagram to docs
• Ensure existing tests still pass
• Add explicit tests that cover all functionality of keyboard, mouse and touch sensors
• Test on more devices
• Block container scrolling for touch dragging
• Re-add previous window reference grabbing Incorrect Binding to Window Event Listeners #139
• Test bindings still work in ie11
• Remove array.includes :(
• Add test for aria-grabbing
• Remove 'DragTypes' from drag-handle-types
• Remove drag-handle.old
• Write release notes
• Screen cast

[alexreardon]

@jaredcrowe I still have a lot of tests to finish but the /src code is in a fairly good state

[alexreardon]