Add timing information

[mmiller-max]

Both testcase and testsuite attributes require a time attribute, and testsuite elements additionally require a timestamp attribute.

I don't think it will be possible (without it being super complicated) to time individual testcases (@test, @test_throws etc)

[oxinabox]

We might be able to time indivual testcastes by:

• Given each ReferenceTestSuite a last_record_time set to now() when created, and whenever record is called.
• each @test will call record whenever it completes. So we just assign all time between last_record_time and it's calling record to that testcase

TestReports.jl/src/testsets.jl

Line 31 in 1aa41e1

record(ts::ReportingTestSet, t) = (push!(ts.results, t); t)

[mmiller-max]

Oh yeah that's a great idea, nice one. I'll give it a go on the branch I'm working on