Show selected package information in Manage Packages dialog.

When a package is selected the following package information is shown on the right hand side of the dialog:
  Created by
  Version
  Authors
  Downloads
  Package description
Fix blank package summary in Manage Packages dialog packages list.

Display NuGet package description if the summary is missing.
Manage Packages dialog now supports installing/uninstalling packages.

Buttons added: Add/Remove and Manage.
No support for adding/removing packages for multiple projects in a solution.
No support for accepting a package's license agreement.
Remove obsolete menu items.

Install, Uninstall and Update package menu options now removed.