Revamped directory structure of plugins and config files.

Plugin preferences are now in a separate directory tree from their DLLs.

New structure is:

Config
  - Application
    - bdhero-gui.log.config
  - Plugins
    - Tmdb
      - Tmdb.config.json
Plugins
  - Tmdb
    - TmdbPlugin.dll
Added InnoSetup installer scripts.  Automatically downloads .NET 4.0 if necessary.
Updated DependenciesDir from MyProgramDependencies to deps
Allow user to cancel .NET 4.0 install
Used ultra64 LZMA compression in InnoSetup
Minor/ignore - Added comment w/ URL of CodeProject page to InnoSetup/setup.iss
Require XP SP3 or higher in InnoSetup