Added the known issue of build failure after package upgrade in VS2012
Updating the Installing NuGet page to explain the clients
"Command-Line Utility"
Updating installation screen shots and details
Make visited links the same color as unvisited links (the grey was hard to identify as a link).
Make download links more discoverable
Formatting tweaks
"NuGet Client Tools"
Updated heading
Merge branch 'master' into nuget-next