Document Benchmark::Timing.
Document Benchmark::IPS.
Document Benchmark::IPS::Report.
Document Benchmark::IPS::Job.
Remove unused #as_action? in Benchmark::IPS::Job::Entry.
Update README.md (details below).

* Add badges: version, docs.
* Update travis-ci's badge to use .svg.
* Update repositroy link to https.
* Add documentation link.
* Add missing period.
* Update calculation example result.