Update demo
Use properties for the caches and fetcher
Revert back to a far simpler implementation
Safe gaurd against cancellations
Fix warnings in demo
Fix documentation warnings
Add iPhone 5 default image
Merge commit '9d635b1'

Conflicts:
	DCTImageCache.xcodeproj/project.pbxproj
	DCTImageCache/DCTImageCache.m
	DCTImageCache/DCTImageCacheAttributes.m
	DCTImageCache/_DCTImageCacheDiskCache.m
Fix warning about copy + readonly attributes