Viewport meta tag using the attribute 'property' instead of 'name'  - possible fix #405

Possible Fix #405 
The viewport meta tag is using the attribute 'property' instead of 'name' which is preventing the e107 bootstrap responsive theme behave adaptively with device size when an actual mobile device with 480x800 px resolution was used to test. Replacing the 'property' attribute with 'name' attribute fixes the issue. The meta tag attribute name of 'property' is used in OG meta protocol only I believe.

Ref. links to developer notes on meta viewport for some major browsers:
https://developer.mozilla.org/en-US/docs/Mozilla/Mobile/Viewport_meta_tag
http://developer.apple.com/library/safari/#documentation/appleapplications/reference/SafariHTMLRef/Articles/MetaTags.html
http://dev.opera.com/articles/view/an-introduction-to-meta-viewport-and-viewport/