Add URL scheme for OAuth callback

the redirect URI listen2oauth://callback will now be used to
authenticate the user.
Configure initial OAuth flow

The AppDelegate now has a simple test to perform a user authentication
and accept a redirect callback.
Add Provisioning Profile Changes

set up the Build Settings to run on my device.
Add Login View Controller and associated view
Hook login button to method that performs auth

The simple test code has been moved from the AppDelegate into an
IBAction function within the login controller. When the login button is
clicked, the app will open the login page for authentication in the
device’s default browser.
Add Constraints to Storyboard

Constraints are added to adjust to Auto Layout :)
Merge branch 'dev' of https://github.com/bitstatic/listen2 into dev

Conflicts:

Listen2.xcodeproj/project.xcworkspace/xcuserdata/user.xcuserdatad/UserIn
terfaceState.xcuserstate
Refactor code to prepare for callbacks
Merge branch 'dev' of https://github.com/bitstatic/listen2 into dev
Add reference to ClientData file, which was somehow missing

Things got hairy for a while due to source control issues. Hopefully we are now past our bumpy start. The gitignore file likely needs to be updated.
Add gitignore

I can't believe I forgot to add this right away. This is embarrassing. Future commits shouldn't break the repo anymore :/
Make gitignore more thorough in removing user files
Add login button

Added a login button for Spotify
Hook up IBAction to newly added Login button

I am unsure about which we'll end up keeping, so for the moment, both the tappable logo and button are hooked to the same IBAction.
Add Activity Feed prototype

An activity feed TableViewController has been added, along with its associated view on the storyboard and some art assets.
Customize table view insets to match color scheme
Add happy path for retrieving a Spotify session from archive

In the case that a session archived with NSKeyedArchiver is present in the documents directory, that session can be returned for API calls. The sad path (where the session is renewed, or new authentication is required) is forthcoming.
Continue implementation of SpotifySession singleton class

After a bit of research, there are three possible solutions to solving my problem of safely notifying the receiver of a session of success or failure:

* using delegate and datasource protocols to notify the receiver of success or failure as well as to actually provide the requested session
* using NSNotificationCenter (from what I've read, this would be very bad form for this situation)
* using a completion handler; this would involve quite a complicated series of logical statements.

I've therefore decided to go with implementing protocols, as this seems to be the most elegant solution.
Complete the SpotifySession class (for now)

I've provided better documentation and organized the code a bit more. I've also finalized my decision to go with a delegate/datasource pattern.
Fix auto-layout issues and ensure consistency across devices