(WIP) When the ServiceMatrix license has expired and user opens an existing solution, the canvas will be disabled.

Relates to #280 

@esculli -
**What I did**
- What I wanted to do was have a property that's based on teh license expiration that can be used to disable/enable things on the canvas. 
- We have one here,(https://github.com/Particular/ServiceMatrix/blob/release-2.0.0/src/ServiceMatrix.Automation/Model/Application.cs#L292)  but I wasn't sure how to get that in the Diagram's ViewModel.
- So, as a shortcut, i added a globalSettings class that I can bind to.

**Questions:**
1. Can we get rid of the GlobalSettings class and have the boolean currently being set in Application.cs to the view model? 
2. Any other suggestions?

**ToDo:** 
Let;s say, when I started VS, license has expired and I choose to open the solution anyway, the canvas is disabled. I close the solution and this time enter the license. But looks like I'll have to restart visual studio. Maybe I am missing something

cc/ @andreasohlund