For CI - reenable URHO3D_ANGELSCRIPT build option for Appveyor CI.

Close #2362

.appveyor.yml

@@ -72,8 +72,6 @@ before_build:
     ) else (
       call "C:\Program Files (x86)\Microsoft Visual Studio\2017\Community\VC\Auxiliary\Build\vcvars32.bat"
     )
-  # Temporarily disable AngelScript as VS 2017 15.8 cannot handle it
-  - set "URHO3D_ANGELSCRIPT=0"
 build_script:
   - rake ci && if "%PACKAGE_UPLOAD%" == "1" rake ci_package_upload
   - rake ci_timer