pastes: Display 'created at' timestamp

Stupid `stat` differs on osx (bsd) and linux (gnu).. at least we limit
filemtime() to $count number of files.

This closes #2.

Signed-off-by: Carl Helmertz <helmertz@gmail.com>
handle_post: Don't create empty paste

But, redirect anyway so we don't get the fugly "Really wanna post data
again?" popup in the browser.

Signed-off-by: Carl Helmertz <helmertz@gmail.com>
janitor: Remove render_paste()

Hey, we're letting the web server go get the static files for us since a
while ago.. that's a win. Btw, forgot to mention that
wget tad/02353
actually creates the text file 02353, whilst
wget tad/\?id=02353
creates the very unattractive file tad/?id=02353

Signed-off-by: Carl Helmertz <helmertz@gmail.com>