Merge branch 'feature/appveyor-sign-next-branch' into develop

* feature/appveyor-sign-next-branch:
  Appveyor update to sign msi on the `master` and `next` branches (trial & error - attempt #5) - append powershell command for signing
  Appveyor update to sign msi on the `master` and `next` branches (trial & error - attempt #4) - append powershell command for signing

appveyor.yml

@@ -36,7 +36,7 @@ for:
       - master
       - next
 
-  build_script:
+  after_build:
   - ps: Write-Host 'signing MSI file'
   - ps: (& @((Resolve-Path -Path "${Env:ProgramFiles(x86)}\Windows Kits\10\bin\10*\x86\signtool.exe").Path)[0] sign /t http://timestamp.verisign.com/scripts/timstamp.dll /n Blockstack /f signcertfile.pfx BlockstackSetup.msi)
 
@@ -45,5 +45,5 @@ for:
     except:
       - master
       - next
-  build_script:
+  after_build:
   - ps: Write-Host 'skipping signing MSI file'