Hi dear,
it s not matter of plugin. I saw in an shared hosting that a kind of service offered by the provider, and which name is SITEAPPS, for strange reasons, insert that code in YOUR code.
This happen, when you have activated the SITEAPP service for your domain. So if you want solve, just deactivate that service on your domain.
Here the code… from siteapps
http://support.siteapps.com/entries/490014-Implementing-SiteApps-tag-on-your-site-for-the-1st-time-
Hope can help