Revert "Campfire: don't feed raw scalar reference to curl"

This reverts commit 5efaf6b086abbd73c51a185cf14516bd7dc9316f.

It now seems broken on more recent versions of curl/perl.
Again, I'm still unsure of the exact cause or broken
version. But given that the original commit was to make
debian squeeze happy, and it's now mostly obsolete, let's
just revert.