Fix: meta-section in generated markup must not be placed absolute in single-column view

This patch fixes the somehow ugly behavior of the single-column view, especially in the fruit-company's mobile safari. As a result the file-path is now visible in single-column-view too. A fixed result is [here](http://sjorek.github.io/groc/). Narrow the window to activate the single-column view and compare this with the [original result](http://nevir.github.io/groc/).

The problem is (or was) that the generated div#meta is positioned absolute with a left gap of 33em - in both views, the single-column-view (body's max-width ≤ 33em) and the double-column-view (body's max-width ≥ 33em). For the latter this is absolutely correct, but in single-column view it overflows the body to the right, hence browsers having a viewport and interpreting the given CSS as it is (instead of trying to fix visual-layout on the fly) tend to behave funny if one scrolls to the right. If something is placed outside the body's canvas and not hidden (<- !) the viewport tries to enlarge the window to include the missing element and give the user a chance to glimpse at what ever has been placed there. Many viewport-implementations have this behavior documented, not just the fruit-company's browser.

Hope you like this fix as it should at least enhance the (mis-)behaviors of issue https://github.com/nevir/groc/issues/1 … :cold_sweat: 

Cheers,
Stephan

ps: If you need screenshots of the iPhruit*-devices (dunno if you have access to mobile-safari) ping me back …
pps: I have only access to the fruit company's iPhruit*-Simulators, and no other comparable device, so anybody having real hardware could double-check the result here: http://sjorek.github.io/groc/
ppps: Yes, I'm one of the few guys out there, refusing to have a smartphone at all, although I could easily afford one … :smiling_imp: 

*) _iPhruit_: the symbiosis of the fruit-companys iDevices and the word _fruit_, using the latin _f_ equivalent _ph_ as in my name above …