travis: use direct link for GnuPGInterface
travis: drop py2.5 as we can't run self-test there now
travis: make pep8 less strict now
Use py2.6+ except style
Use py2.6+ print style
Remove unused imports
Remove/comment/refactor unused variables
Remove functions and class, which will be defined later
Don't use starred imports
travis: do the initial setup and rescan during travis check