added xgboost building in windows script

build_windows_dependencies.bat

 @echo off
 
+cd xgboost
+git submodule init
+git submodule update
+mkdir build
+cd build
+cmake .. -G "Visual Studio 14 2015 Win64"
+msbuild xgboost.sln /m /p:Configuration=Release /p:Platform=x64
+
+if %errorlevel% neq 0 exit /b 1
+
+cd ../python-package
+python setup.py install
+
+if %errorlevel% neq 0 exit /b 1
+
+cd ../..
+
 cd alphamind\pfopt
 
 call build_windows.bat