Revert "New release build of libcurl 7.34.0 and lib cares 1.10.0 d5d3871"

This reverts commit f18ae34d8ebefca67ca3fee9fe3b18db5086162e.

Going back to libcurl 7.31 since our current 7.34 build references
kSecImportExportPassphrase which breaks OS X 10.6 compat.
https://karelia.fogbugz.com/f/cases/236223