Added upload method constant for PATCH and a check
that the uploadMethod is rightly set with only one
of the three allowed constants.
Moved widgetId file variable to be an instance
variable and initialized it to a unique identifier
Reverting the cup:willUseURLForFile: delegate
method. Not used anymore. Adding an instance 
variable on CupFile instead.
Reverted CupDefault constants
Whitespace fix
Added and fixed comments
Reinstated callbacks file variable but made it
an instance variable
Reverted code with no meaning