Fixed #21 - missing octokit dependency in nuget package

Author: Jake Ginnivan

GitReleaseNotes.nuspec

@@ -17,6 +17,7 @@
     <file src="GitReleaseNotes.exe" target="tools"/>
     <file src="GitReleaseNotes.pdb" target="tools"/>
     <file src="Args.dll" target="tools"/>
+    <file src="Octokit.dll" target="tools"/>
     <file src="LibGit2Sharp.dll" target="tools"/>
     <file src="NativeBinaries/amd64/git2-11f8336.dll" target="tools/NativeBinaries/amd64/"/>
     <file src="NativeBinaries/x86/git2-11f8336.dll" target="tools/NativeBinaries/x86/"/>