Add a flag for disabling Powershell

src/config.rs

@@ -23,6 +23,9 @@ lazy_static! {
         m.insert("emacs", Step::Emacs);
         m.insert("gem", Step::Gem);
 
+        #[cfg(windows)]
+        m.insert("powershell", Step::Powershell);
+
         m
     };
 }

src/main.rs

@@ -131,9 +131,12 @@ fn run() -> Result<(), Error> {
     #[cfg(windows)]
     let powershell = windows::Powershell::new();
 
+    #[cfg(windows)]
+    let should_run_powershell = powershell.profile().is_some() && config.should_run(Step::Powershell);
+
     #[cfg(windows)]
     {
-        if powershell.profile().is_some() && config.should_run(Step::Powershell) {
+        if should_run_powershell {
             execute(
                 &mut report,
                 "Powershell Modules Update",