Coherent net451 framework usage

Author: cgravill

paket.dependencies

@@ -2,7 +2,7 @@ source https://www.nuget.org/api/v2
 
 nuget FSharp.Compiler.Service 6.0.2 framework: >= net451
 nuget NetMQ 3.3.3.1
-nuget Newtonsoft.Json ~> 9.0.1 framework: >= net45
+nuget Newtonsoft.Json ~> 9.0.1 framework: >= net451
 nuget FAKE
 nuget xUnit >= 2.1 framework: >= net451
 nuget xunit.runner.console >= 2.1 framework: >= net451