Update README.md
Merge in core split work
Set all projects to .NET 4.0
Merge remote-tracking branch 'origin/Revit2015' into Revit2016
Resolve Surface conflict.
ShouldDisplayPreviewCore is a property, not a method
Revert changs in CS.props file
Fix changes to RevitNodesUI.csproj
Remove .NET 4.5 framework version prop from test csproj files
Merge pull request #51 from pboyer/DynamoCoreSplitRevit2016

Dynamo core split : Revit2016
Updated RaaS dll's for NodeCustomization changes
Merge pull request #53 from pboyer/DynamoCoreSplitRevit2016

Updated RaaS dll's for NodeCustomization changes