Added Build base script and NuGet.exe

Base setup for FAKE: added NuGet.exe in tools folder, and build.bat /
build.fsx.
Clean & Build added to build script.
AssemblyInfo, nuspec and NuGet build

Added AssemblyInfo.fs and nuspec file.
Completed build to create NuGet package.
Merge pull request #25 from mathias-brandewinder/master

Automated NuGet package build using FAKE