Exclude Microsoft.WSMan.Management from the list of default snapins

Fix #1180

test/powershell/engine/BasicEngine.Tests.ps1

@@ -0,0 +1,7 @@
+Describe 'Basic engine APIs' {
+    Context 'powershell::Create' {
+        It 'can create default instance' {
+            [powershell]::Create() | Should Not Be $null
+        }
+    }
+}