(Re)fixes issue where `unreadMessageCount` was incremented when composing a new message.

When user starts composing a message, now marking it as `sentByUser` and `seenByUser`
Fixes #70
Fixes IOS-310
CC 7b80707f8f78736d62ce0a1e97dd30ee42e37a1b
Logging when Feedback Demo receives new Apptentive notifications.
Fixed issue where initial configuration was not updating on first launch.
Now updating the configuration after conversation is created.
Logging additional info about rating flow configuration.
Fixes IOS-341
Fixes IOS-356 Can't see send button in Message Center with white tintColor

Adding a tintColor property to ATConnect. To test, in FeedbackDemoAppDelegate, add:

       [self.window setTintColor:[UIColor whiteColor]];

and see the resulting problem with our UI with a white tint color. To override the tint color, add:

       [[ATConnect sharedConnection] setTintColor:[UIColor redColor]];

which will use a red tint color in our UI.
Merge branch 'Next' of github.com:apptentive/apptentive-ios into Next
Added `hidden` property on ATAbstractMessage
Added new v4 xcdatamodel with `hidden` property
Added v3 to v4 xcmappingmodel
Added tests for v3 to v4 Core Data migration.
Sending `hidden` property to server
Ignore hidden messages in iOS client’s Message Center
Moved image/file message sending code to ATBackend
Added API methods for hidden attachment messages
Don’t attach custom data to hidden messages
Displaying Intro Dialog rather than Message Center until there are > 0 *non-hidden* messages.
Fixing analyzer warning/potential crash caused by bad merge.
Merge branch 'Next' of github.com:apptentive/apptentive-ios into Next
Set default value of ATAbstractMessage’s `hidden` property to `NO`
Regenerated v3 to v4 mapping model
In the Readme, now setting API key in `application:didFinishLaunchingWithOptions:`
If `application:didFinishLaunchingWithOptions:` is present (Xcode default), the former `applicationDidFinishLaunching:` will not be called.
Thus a developer exactly following our directions might never set the API key.
Adding some unit tests around upgrading messages and the hidden field.
Adding documentation on recent changes.
Fixing IOS-172 Prevent duplicate Message Center automated messages
Fixes IOS-355 Strip whitespace from Survey text response