Even though it doesn't matter here because it is going from one side of
the parent all the way to the other. I hope it makes it easier if we
completely avoid right/left and only ever use start/end. Then searching
for RTL problems will be easier.
This is as per the mockup in issue #840, and does the following:
* Adds a new `PreferencesCategory` of "My Apps" at the top of the
preferences screen.
* Adds a "Manage Installed Apps" preference, and moves the
"Repositories" preference into this category.
* Repeals an existing change which prevented "updateable" apps from
appearing in the list of "installed" apps. This is because the two
lists of apps are no longer displayed alongside eachother.
* Enhances the `AppListItemController` to also be able to display
whether or not the currently installed version is the recommended
version or not.
* Also adds option to display whether the user has asked to ignore any
updates for any specific apps.
