Add transitions when an image or webview is done downloading.
Also change default placeholder image to NoRuler.jpg instead of the blank white
image.
Restructure category data/logic for CategoryViewController

On iFixit, we want to keep the distinction between categories and devices.
On Dozuki we want to merge that distinction, and just have categories. For some
context, this code modifies the UITableViewController that is responsible for
presenting a list of categories to the user to drill down and finally select a
guide.I tried to simplify things, I feel they were overly complicated before.
This also makes it easy to make future changes regarding differences between
iFixit/Dozuki, in case Taylor changes his mind =).
Update CategoriesViewController.m

Remove unneeded comparison
Merge pull request #18 from iFixit/restructure-category-and-tableview-log

Restructure category data/logic for CategoryViewController
Stable version
functionality for iPhone added
progress
later stabler, I will rebase this stuff
Implement a whole bunch of things
Merge branch 'master' into modify-ui-to-be-more-consistent

Conflicts:
	Classes/CategoriesViewController.h
	Classes/CategoriesViewController.m
Merge pull request #22 from iFixit/modify-ui-to-be-more-consistent

Modify UI to be consistent with iphone/ipad, add more features related to navigation