Included note about Windows and WinRT projects

Resolves #143
Merge pull request #146 from octokit/shiftkey-patch-1

Included note about Windows and WinRT projects
Update NuGet to 2.71, since the old version can't access the feed.
Sound check - FAKE can be downloaded and is running with the buildWithFAKE.cmd.
Adding Clean and CopyAdditionalFiles targets to the build script.
Adding simple BuildApp target to the build script.
Copy more files to the nuget packaing path in the build
Copy the files to the Octokit.Reactive packaging path in the build
Create the Octokit NuGet package with the NuGet task as discussed in #116
Create the Octokit.Reactive NuGet package and set dependencies to Octokit as discussed in #116
Fixing the packaging paths in the build script.
Running the Octokit tests
Prepare an IntegrationTest target - TODO: How to set this up?
Remove old build script - we can use FAKE as default.
Fixing the build output paths.
Retrieve the dependent Rx-Main version directly from the installed version in the packages dir.
As discussed in #118 we use environment variables. This should work.
Small cleanup in the build script.
Restore Nuget packages during the build.
Retrieve the version from the ReleaseNotes.md