Metadata tweaks and updates

Lots of cleanup to make things a bit more standardized.

Remove Synology metadata since it was just a clone of MB and does not appear to be actually used by synology units.

Add banner, season banner season all poster and season all banner options.

Remove use_banner poster override since now we have a banner option.
  This now means users can have both a poster and banner instead of one or the other (XBMC12+).
  Migrate legacy XBMC poster + use_banner setup to just banner option (keeps old functionality).
  Notice that on XBMC the banner and poster result in the same name,
  if you have both checked it will just create folder.jpg with a poster
  since we don't overwrite existing metadata.
Merge branch 'change_metadata_updates_PR-789-thezoggy' into development

* change_metadata_updates_PR-789-thezoggy:
  Metadata tweaks and updates

  closes gh-789 closes gh-621