Define interface for classes that read menu items metadata

Any class that attempts to read metadata for menu items
must conform to MenuItemsReader protocol.
Read menu items metadata from a plist

Currently we store metadata for each menu item in
a plist. In the future it can easily be provided through
other means such as retrieving it from a remote
service.

Since we've created a protocol for reading menu items
metadata (i.e., MenuItemsReader), all we need to do is
create a new class that knows how to read menu items
from a remote server and conforms to the MenuItemsReader
protocol. After that we can easily replace MenuItemsPlistReader
with the new class.
Build MenuItem objects from raw data
Add a table view to menu view controller
Create a default data source for menu table
Define a notification that gets posted when a menu item is tapped
Create a correct tap handler for each menu item
Import ECSlidingViewController category on UIViewController

It's not enough to import just ECSlidingViewController.h since
the category is defined in a separate Objective-C file.
Remove sliding navigation controller

The new setup for ECSlidingViewController doesn't need
a custom subclass of UINavigationController. AppMenuManager
will be responsible for creating all the necessary classes and
associating them to make a functional app menu.
Create App Menu Manager

This manager class is responsible for setting up
all the dependencies for each classes involved in
creating a fully functional app menu.
Create an empty houses view controller
Create an empty realtors view controller
Create an empty settings view controller
Check in all project level changes thus far

It's usually a bad practice to checkin all project level
changes as one commit because it makes it hard to
revert the effect of each individual commit. But in the
interest of time, i am being naughty here.