Fixes for issue #14.
Fixes for issue #14.

* Rescue on rtf decompression had been commented out since 8933c26e.
  All test files had rtf content, but this broke non-rtf files.
* Further, body_html attempted to always read from the property but
  it may also be a string instead of a stream.
* Above issues had been hidden by use of rescue nil, conflating
  non-exceptional case of not having property, with actual error case.

mvz/ruby-msg,mysociety/ruby-msg,packages/ruby-msg,zhivko/ruby-msg,zhivko/ruby-msg,packages/ruby-msg,TheProjecter/ruby-msg,mysociety/ruby-msg,aquasync/ruby-msg,TheProjecter/ruby-msg,mvz/ruby-msg,aquasync/ruby-msg