Check whether net35 is installed

[auduchinok]

build.cmd fails on tests when trying to initialize an empty project if .Net 3.5 is not installed. Possible workaround is to try launching anything that needs the framework before doing anything else which will lead to Windows asking to install the framework.

1) Fake.UnitTestCommon+FailedTestsException: NUnit test failed. Process finished with exit code FatalError (-2146232576).
   at Fake.NUnitSequential.NUnit(FSharpFunc`2 setParams, IEnumerable`1 assemblies) in C:\code\fake\src\app\FakeLib\UnitTest\NUnit\Sequential.fs:line 45
   at FSI_0005.Build.clo@145-11.Invoke(Unit _arg7) in C:\Users\Eugene\Source\Repos\DotParser\build.fsx:line 146
   at Fake.TargetHelper.runSingleTarget(TargetTemplate`1 target) in C:\code\fake\src\app\FakeLib\TargetHelper.fs:line 492

Reproduced on clean Win10 install with VS 2015 Update 2. Work fine after .Net 3.5 install.

[auduchinok]

Seems like it may be connected to #241.

[dsyme]

It's working for me without .NET 3.5 installed. Adding AutoGenerateBindingRedirects may have done the trick