GitHub Announcer, MongoDB settings, Cleanup

[shiftkey]

First off, apologies for the big pull request. Let me outline the changes:

Source Control:

• Extensions now divided into Extensions/Sprockets and Extensions/Announcers. Rearranged in solution too.
• UserVoice announcer now uses NuGet package for JSON.NET.

  Features

• Added GitHub announcer
• Added ILogger interface so that components can display messages in hosting environment
• Added ConsoleLogger to ConsoleBotHost project so that extensions can access console
• Added IsolatedStorageSettingsService to ConsoleBotHost so that announcers can persist settings
• Added MongoSettingsService to AspNetBotHost - this needs settings from AppHb to be injected, so it not being used in Bootstrapper currently.

  Core

• Added Name property to IAnnounce so that host can display human-friendly name of extension
• Updated components which used Bot to now use IBot

[shiftkey]

OH: "69 diffs? fuck you"

Will resubmit separate PRs for rearranging source and features