(#538) - Switch to Linux to test Firefox

I did a review of the bulk_docs code and cannot see where
our tests could intermittently fail, this seems to be a
quirck with FileReader on windows. Linux tests have been
far more stable.

I also removed some redundant error handling code and
unneeded backwards compatibility code
Merge pull request #619 from daleharvey/attach-tests

(#538) - WIP testing if linux is more stable