Avoid using version.all_files (which is cached) in ReviewBase
Avoid using version.all_files (which is cached) in ReviewBase

We're getting some weird IndexError exceptions because all_files
is empty, and I can't reproduce it locally. Using self.files should
be more reliable, the class needs it to sign the files etc.

wagnerand/addons-server,eviljeff/olympia,lavish205/olympia,harry-7/addons-server,diox/olympia,diox/olympia,mozilla/addons-server,atiqueahmedziad/addons-server,eviljeff/olympia,wagnerand/olympia,tsl143/addons-server,mozilla/olympia,lavish205/olympia,kumar303/olympia,aviarypl/mozilla-l10n-addons-server,mozilla/addons-server,mozilla/addons-server,kumar303/addons-server,atiqueahmedziad/addons-server,harry-7/addons-server,psiinon/addons-server,mozilla/addons-server,wagnerand/olympia,atiqueahmedziad/addons-server,mozilla/olympia,bqbn/addons-server,wagnerand/olympia,eviljeff/olympia,tsl143/addons-server,aviarypl/mozilla-l10n-addons-server,harikishen/addons-server,harikishen/addons-server,wagnerand/olympia,wagnerand/addons-server,kumar303/addons-server,eviljeff/olympia,kumar303/olympia,wagnerand/addons-server,psiinon/addons-server,harry-7/addons-server,aviarypl/mozilla-l10n-addons-server,tsl143/addons-server,harikishen/addons-server,bqbn/addons-server,psiinon/addons-server,harry-7/addons-server,lavish205/olympia,harikishen/addons-server,kumar303/olympia,aviarypl/mozilla-l10n-addons-server,lavish205/olympia,bqbn/addons-server,bqbn/addons-server,kumar303/addons-server,mozilla/olympia,diox/olympia,atiqueahmedziad/addons-server,tsl143/addons-server,kumar303/addons-server,mozilla/olympia,diox/olympia,psiinon/addons-server,wagnerand/addons-server,kumar303/olympia