Update nuget build to include .NET 4.5.1.

Author: babelshift

SteamWebAPI2/SteamWebAPI2.nuspec

@@ -18,6 +18,9 @@
     <file src="..\bin\Release\portable\SteamWebAPI2.pdb" target="lib\portable-net452+win81\SteamWebAPI2.pdb"/>
     <file src="..\bin\Release\portable\SteamWebAPI2.dll" target="lib\portable-net452+win81\SteamWebAPI2.dll"/>
 
+    <file src="..\bin\Release\net452\SteamWebAPI2.pdb" target="lib\net451\SteamWebAPI2.pdb"/>
+    <file src="..\bin\Release\net452\SteamWebAPI2.dll" target="lib\net451\SteamWebAPI2.dll"/>
+	
     <file src="..\bin\Release\net452\SteamWebAPI2.pdb" target="lib\net452\SteamWebAPI2.pdb"/>
     <file src="..\bin\Release\net452\SteamWebAPI2.dll" target="lib\net452\SteamWebAPI2.dll"/>