Add NSIS installer script file.

Add build_release.bat file which handles the build process for all supported
Windows versions. All files generated by this script are test-signed.

build_release.bat assumes following:
  * User is running x64 version of Windows
  * WDK 7.1.0 is installed
  * Microsoft Visual Studio 2012 Professional or above is installed
  * Windows Driver Kit 8 is installed