rebase: remove extraneous blank at the end of file

run-tests: include 'start' and 'end' in --time output This is useful information to understand what is taking time in tests. Both are included because I can see myself sorting this output using shell script. Having both data makes it much easier than extracting 'start'+'real'.

run-tests: track start and end time of tests We currently have information about how long each test took, but we have no data about their actual scheduling. So we now track when a test started and stopped (in the referential of the whole tests run) to expose this information. The data is currently in the json only because the json output is meant to be extensible. Later changeset will includes this data in the text output and we will be happy to bikeshed its formating there. Yes, "end" is actually just "start" + "time", but computing it an including it in the output is simple, cheap and convenient.