Added Find Owning View Controller command

Shortcut is `fovc`. Given an input `UIView` this command will walk the next
responder chain until it fines the UIViewController that owns this view.
Fix description for fovc command

Fixes comment at https://github.com/facebook/chisel/pull/13/files#r10396271
Add found view controller to pasteboard
added commands to show NSData as string and image
Fixed a crash which happened when trying to show views or layers from 64-bit simulator.
Fixed an issue which prevented graphics context from being created on 64-bit devices.
Handle int conversion exceptions
Merged show{view,layer,image,imageref} into visualize.
Updated README for visualize.
Added an error message if visualize in invoked on unsupported class.
Removed BOOL casts.
Renamed a variable, fixed a typo.
Removed unnecessary parentheses.
Merge pull request #22 from antons/master

Fixed issues which prevented show view and layer commands from working on 64 bits
Added object helpers for class checking.
fix bug in example defining a custom command

Example code in readme used two different names for the class defining
the example code, resulting in an error when attempting to load the new
command.

This fix just updates the code to use the same name consistently, so
that the example works.
Merge pull request #28 from algal/master

fix bug in example defining a custom command
Add upwards option to pviews command
Update README.md
Merge pull request #29 from facebook/pviews_upwards

Add upwards option to pviews command