Added offset x/y functionality

This will give users ability to handle screen boundaries
Allowed for multiple context menus on page

Moved the hiding/showing into the widget object. Call the fadein/fadeout using $.proxy.

Before having multiple different context menus only showed/hid the first menu properly.  Now you can show as many as you like and they will properly hide each menu using their own context.
put in screen detection mode (enabled by default)

Enabled:  will adjust the x,y coordinates based on screen width/height.
Merge pull request #4 from jlipford/master

Added offset X/Y functionality