phantomjs stout stderr

[freb]

http://lua-users.org/lists/lua-l/2010-09/msg00955.html

Now that we have timeout working, we should probably spend some time implementing proper error handing into http-screenshot.

Lua doens't have great support for handing the otuput streams from the phtantomjs command. I think the best we can do is pipe the output from stderr to one file, stdout to another file. Phantomjs seems to support stderr and stdout: https://github.com/ariya/phantomjs/blob/master/examples/stdin-stdout-stderr.js