Rename 'torquebox war --env' to 'torquebox war --envvar'

The '--env' had a different meaning than 'torquebox run --env' and was
confusing. I'm not sure envvar is much better, but at least it's
different.
Make torquebox jar --envvar description a bit clearer
Add a test for Rack::Deflater usage

This required also adding an option to specify the
rackup file when creating a war.