WIP:  removing dependency on AFNetworking -- replacing with lightweight category, `UIImageView+AutoLayoutCells`
Refactored `UIImageView+AutoLayoutCells` into multiple files (per Single Responsibility principle)

WIP: Need to add tests for `UIImageView+ALImageWithURL` and `ALImageCell`
Fixed issue where image download tasks would still continue after an image view's image was set and upon completion set the image to an old downloaded value.
Example workflow:  (1) task started, (2) image set, (3) task complete and sets image)

WIP: need to add missing unit tests
Added unit tests, still need to add a few more.
Added missing tests for `UIImageView+ALImageWithURL`
1) Added missing tests for `ALImageCell`
2) Simplified `ALBaseCell` -- got rid of `notificationCenter` method (left behind due to previous testing setup)
3) Minor code formatting
1) Moved `UIImageView+ALActivityIndicatorView` and `UIImageView+ALImageWithURL` to a new `SharedCategories` folder.
2) Updated pod spec to add new sub spec called `SharedCategories`
3) Updated demo project's pods (resulted in changes to demo's `Podfile.lock`)
1) Replaced dependency on `UIView+AORefreshFont` with `UIView+ALRefreshFont` and `UIFont+ALCustomDynamicFont`... also allows custom fonts to be refreshed too
2) Fixed issue related to `UIImageView+ALImageWithURL` download task completing without error or downloaded file... Currently -- retrying download in such cases (To-do: look for better solution to this, if possible)