[WIP] Metro/MessageDialogs V2

I am trying to make the dialog system very abstract so that a user can plug in their own dialogs. A major revision of #764.

### TODO List:
 - [x] Make every abstract.
 - [x] Implement ProgressDialog
 - [x] Implement SimpleDialog where you can put arbitrary controls in it. ( Suggested by @flagbug )
 - [x] Animations (basic). More animations will come in the next revision.
 - [x] Fix bugs
 - [x] Drink milk. ![img](http://fc03.deviantart.net/fs71/f/2013/233/b/b/rwby_milk_by_dinochickrox-d6j64di.jpg)
 - [x] Make ProgressDialog useable for the general public. Specifically [this](https://github.com/Amrykid/MahApps.Metro/blob/abf26c4a2bf4e291dcb6bc58e782b7e5e52b225c/MahApps.Metro/Controls/Dialogs/MetroWindowDialogExtensions.cs#L63) and return a "remote control" object so you can alter the dialog while its in view.
 - [x] Remove (random/accidential?) clickonce stuff from the .csproj file.
 - [x] Document code.

### Screenshots
#### Message Dialog
![md-v2](https://f.cloud.github.com/assets/251501/1510016/c14bbd88-4a6e-11e3-9d94-0438ffbfcad7.PNG)
![md-v2-2](https://f.cloud.github.com/assets/251501/1510017/c15708b4-4a6e-11e3-8d16-388d3f60e48b.PNG)

#### Progress Dialog
Note the Indeterminate ```MetroProgressBar``` on the bottom of the dialog. The ```ProgressDialog``` is inspired by a similar construct in Github for Windows.
![pd-v2-1](https://f.cloud.github.com/assets/251501/1510011/b5fa8306-4a6e-11e3-93a4-184ae8f04dbf.PNG)
![pd-v2-2](https://f.cloud.github.com/assets/251501/1510012/b609c64a-4a6e-11e3-8f59-50b29a0e6049.PNG)
![pd-v2-3](https://f.cloud.github.com/assets/251501/1510013/b613750a-4a6e-11e3-973a-99f07c6ad68d.PNG)
![pd-v2-4](https://f.cloud.github.com/assets/251501/1510014/b61715f2-4a6e-11e3-8253-ed7289d13491.PNG)

#### Simple Dialog
![sd](https://f.cloud.github.com/assets/251501/1510019/d53b3832-4a6e-11e3-9080-f63e6801cb34.PNG)

##### Dark
![pd-dark](https://f.cloud.github.com/assets/251501/1510025/05bc0c2a-4a6f-11e3-9f82-0d39cbebf905.PNG)
![md-dark](https://f.cloud.github.com/assets/251501/1510026/05cb47ee-4a6f-11e3-8523-cd29ce1af67d.PNG)


### Breaking Changes
- Dialog methods were moved outside of ```MetroWindow``` to extension methods. This was to remove clutter and ugly code from MetroWindow.cs.