Added missing MSBuild.Node.nuspec file

Close #1
Fixed included files for Gulp nuspec
MSBuild.NodeTools should not include any build/ files, the dependencies handle that
Update README.md
Fixup for the MSBuild.Gulp package.
Merge pull request #3 from DaveVdE/development

Fixup for the MSBuild.Gulp package.
Fix all the nuspec files
Push versions to 0.2.1
Release 0.2.1

* development:
  Push versions to 0.2.1
  Fix all the nuspec files
  Fixup for the MSBuild.Gulp package.
  Update README.md
  MSBuild.NodeTools should not include any build/ files, the dependencies handle that
  Fixed included files for Gulp nuspec
  Added missing MSBuild.Node.nuspec file