.travis.yml: add pypy3
.travis.yml: pipe exit of requirements.txt to true
.travis.yml: comment allow failures
.travis.yml: fix detection of major python version

and clearly tell us what it is.
.travis.yml: use `sys.version_info[0]`
SilencePlugin: Fix crash when a message with a percent character is sent.
Merge pull request #221 from Mkaysi/travis

Try to fix Travis
AttackProtector: prevent testKban from breaking other tests by messing with schedule.
Variables & WebStats: Fix Pypy3 compatibility.
.travis.yml: Skip some plugins on Python 3.