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Add secureftp-test.com to refrences
Note SYST support in
Close code injection vulnerabilit in LIST and NLST.

This is quick piece of plywood over the hole.  It still allows
arbitrary ls switches (yuck), and breaks globbing.  LIST and NLST need
to be rewritten to not shell out to ls.

The vulnerability was discovered by Larry. W. Cashdollar.
Version bump to 0.2.2
Regenerate gemspec for version 0.2.2