Merge pull request #1464 from PowerShell/kkaczma/mc

Fixing mc.exe detection and installing required tools in Start-PSBootstrap. Fixes #1451

appveyor.yml

@@ -17,7 +17,7 @@ install:
   - ps: Set-Content c:\users\appveyor\.ssh\id_rsa $fileContent
   - git config --global url.git@github.com:.insteadOf https://github.com/
   - git submodule update --init
-  - ps: Import-Module .\build.psm1; Start-PSBootstrap
+  - ps: Import-Module .\build.psm1; Start-PSBootstrap -Force
 
 build_script:
   - ps: |