Allow subclasses to override cache key and background tag for cell background images, since we allow them to override imageForFirst:last:highlighted:drawDivider:. This way the caching facility of imageForFirst:last:highlighted:drawDivider: can be used by subclasses that override that method but call super.
Merge pull request #528 from darrenw/CellBackground

Allow NICellbackground subclasses to override cache key and background tag for cell backgrounds.
[networkimage] Suppress warning about formatting values to strings.
[networkimage] Implement basic maxAge support again.

Closes #286.
Update AFNetworking to 2.2.1.
[core] Deprecate NIInvocationWithClassTarget in favor of NIInvocationWithInstanceTarget.

Closes #531.
Fix for incorrect Switch target/selector  handling on the devices with armv64 architecture
Merge pull request #534 from PaulTaykalo/master

Fix for incorrect Switch target/selector  handling on the devices with armv64 architecture