Merging vNextDialog back into vNext

Firstly.... apologies if these changes cause you any problems... but I've tidied up the source tree in vNextDialog and I think these changes will have positive benefits for all users. So I'm merging the changes back into vNext.

The key details of the changes are:

• Dialogs
• I've added a version of Android.Dialog/MonoDroid.Dialog to the source - this is in CrossUI.Droid
• I've added a PCL library - CrossUI.Core - which contains the shared Dialog/Menu/List code
• I've moved the MT.Dialog code out of MvvmCross Dialog and back into a CrossUI.Dialog class
• AutoViews
• I've added projects for AutoViews - these aren't finished yet... but are a very good step in the right direction!
• I've added an AutoView sample - based on CustomerManagement. This isn't a 'best practice' sample - it's more a 'here's 3 ways of using autoviews' - so may not be easy to follow yet.
• AutoViews currently only exist for MonoTouch and MonoDroid
• Build Paths
• I've changed the build paths so that all the DLLs build into /bin/debug and /bin/release 
• Importantly this means it should be easier to do a binary release of MvvmCross again soon :)
• One side effect of these changes is that you probably won't be able to build both of Droid/Touch at the same time - this is because they will fight over the System.Windows and System.Net Assembly names - but otherwise they should still build individually.
• MonoTouch project configurations
• The MonoTouch library projects are now switched to simpler Debug/Release only - I'll try to maintain this as we move forwards! 

If these changes break your code.... sorry

The main things that will need changing to get you back building are:

• If you were using MonoTouch.Dialog, then you will need to add the CrossUI.Core and CrossUI.Dialog projects and you will need to change some Cirrious.MvvmCross.Dialog.Touch.Elements namespaces to CrossUI.Touch.Dialog.Elements
• If you were relying on the iPhone/iPhoneSimulator project configurations, then you will need to use the Configuration Manager to adjust these back to simpler Debug/Release dependencies.

Sorry again for making these changes so suddenly... but I was informed today that a new user was having problems building the main tree... and I wanted to fix these problems.

This merge back seemed like the best way to fix them and to provide the best possible platform moving forwards.