Merge pull request #122 from rankida/detect-powershell

Added Windows Powershell detection

test/fixtures/hello.ps1

@@ -0,0 +1,2 @@
+# Hello world in powershell
+Write-Host 'Hello World'

test/fixtures/hello.psm1

@@ -0,0 +1,5 @@
+# Hello World powershell module
+
+function hello() {
+  Write-Host 'Hello World'
+}