Imports of guestbook command

PathSynopsis
golang.org/x/net/contextPackage context defines the Context type, which carries deadlines, cancellation signals, and other request-scoped values across API boundaries and between processes.
google.golang.org/appenginePackage appengine provides basic functionality for Google App Engine.
google.golang.org/appengine/datastorePackage datastore provides a client for App Engine's datastore service.
google.golang.org/appengine/logPackage log provides the means of writing and querying an application's logs from within an App Engine application.
google.golang.org/appengine/userPackage user provides a client for App Engine's user authentication service.
html/templatePackage template (html/template) implements data-driven templates for generating HTML output safe against code injection.
net/httpPackage http provides HTTP client and server implementations.
timePackage time provides functionality for measuring and displaying time.