Merge pull request #7 from jkent/use-ci-var

Use %CI% instead of %APPVEYOR%

Author: Sibras

install_script.bat

@@ -325,7 +325,7 @@ SET ERROR=1
 
 :Exit
 cd %CALLDIR%
-if "%APPVEYOR%"=="" (
+if "%CI%"=="" (
     if not defined ISINSTANCE (
         pause
     )