In 0.3.14, command assertions that wrap powershell can no longer asse…

…rt against stdout/stderr successfully (#651)

* Allow command assertion to have configurable shell

In 0.3.14, my command assertions that used powershell.exe to run powershell started to fail, and I suspect the new cmd /c wrapping, so I'm adding an integration test first, then if that fails I'll try to make changes to allow it to pass - I'm expecting to want to make it possible to use powershell as the shell within command assertions to achieve that.

* Hah, of course fails mac

* Adjust quoting per #651 (comment)

* wipe away recon

integration-tests/goss/windows/tests/command.goss.yaml

@@ -7,3 +7,10 @@ command:
     - hello world
     stderr: []
     timeout: 10000
+  wrap a powershell - expect 0 because travis does not restrict anonymous logins:
+    exec: powershell -noprofile -noninteractive -command (get-itemproperty -path 'HKLM:/SYSTEM/CurrentControlSet/Control/Lsa/').restrictanonymous
+    exit-status: 0
+    stdout:
+    - 0
+    stderr: []
+    timeout: 10000