remove cached messages
There should be only one version of a sitemap in the Atmosphere cache for any give UUID.  If more then one exists they are transfered to the client using chunked encoding which is wasteful and currently breaks the IOS client.
Merge branch 'master' into atmos-duplicate-fix
Reverted some chnages that are no longer needed
Merge pull request #1765 from digitaldan/atmos-duplicate-fix

[Atmosphere] duplicate sitemap message fix