TMailParser is unused, and incompatible with Rails 3

refs CNVS-10649

Change-Id: I772731024951bc295b8fb1a9643195ace4a36f0d
Reviewed-on: https://gerrit.instructure.com/28887
QA-Review: Bryan Madsen <bryan@instructure.com>
Product-Review: Bryan Madsen <bryan@instructure.com>
Tested-by: Jenkins <jenkins@instructure.com>
Reviewed-by: Brian Palmer <brianp@instructure.com>