Bug 807155: Fix form string that was broken for l10n.

The text for the privacy policy string was changed recently
for the hacks blog form to add the "target" attribute to
the link for more appropriate behavior when framed. This broke
existing translations however. This commit reverts the string
and uses JS to add the target attribute.
Merge pull request #1 from pmclanahan/rlr-fix-contribute-lang-files

Bug 807155: Fix form string that was broken for l10n.