fixed internal require ordering, use SimpleCov for coverage on ruby >= 1.9, run coverage only when coverage=1 env var
when on CI, generate XML reports using ci_reporter
on 1.8, run rcov by default if coverage flag is set
exclude tests code from coverage
there is no need to cd anywhere
Merge pull request #9 from KenjiTakahashi/119220_jenkins_n_stuff

[119220] Preparations for CI.