(Bug 4882, 4878) Allow truncated subjects for imports/feeds

We recently switched from silent truncation of subjects when posting,
to preventing the entry from posting,  to give the user the chance to
correct it. But that doesn't make sense when we're pulling in entries in
bulk, so let's let this through (old behavior)
Merge pull request #277 from afuna/subject-too-long

(Bug 4882, 4878) Allow truncated subjects for imports/feeds