Bugfix/verloc fixes and adjustments

[jstuczyn]

This pull requests does the following:

• Introduces timeout on trying to establish connection to tested nodes
• Introduces timeout when trying to write packets to tested nodes
• Saves verloc results in tested chunks rather than everything when it's done (i.e. by default writes in increments of 50)
• Adds tested_nodes fields to the verloc result to give indication of how many results are expected
• Adds run_started and run_finished fields to the verloc results to give indication of how old are the results

The added timeouts significantly decrease time it takes for the measurements to complete as some misconfigured nodes will keep the connection in limbo until the OS TCP timeout kicks in (and I'm actually not entirely sure if there are some edge cases that might keep it alive indefinitely hence never allowing verloc to finish, so maybe it's a bugfix after all.)