Run module tests in parallel

[troydai]

Running test modules in parallel. On my machine it reduces running time from 16 minutes to around 9 minutes.

The actual running time is shorter then that. I'm going to profile the test further to figure out where were the time spent on.

Summary
========================
acr        skipped                     
acs        passed  16:38:04  16:38:07  
cloud      skipped                     
component  skipped                     
configure  skipped                     
container  skipped                     
context    skipped                     
feedback   skipped                     
iot        passed  16:38:04  16:38:13  
keyvault   passed  16:38:04  16:38:31  
network    passed  16:38:04  16:42:15  
profile    skipped                     
redis      passed  16:38:04  16:38:07  
resource   passed  16:38:04  16:39:23  
role       passed  16:38:04  16:38:46  
storage    passed  16:38:04  16:39:43  
taskhelp   skipped                     
vm         passed  16:38:04  16:42:45  
webapp     passed  16:38:04  16:39:28  
========================

Running time on CI down to 29 minutes:

And the summary on the CI looks like:

[tjprescott]

LGTM. It think it would be nice to output the elapsed time for each series in addition to (or even in lieu of) the start and stop times.

Recommend @derekbekoe take a look as well since he originally wrote this.

[troydai]

Updated.

1. Print duration instead of finished time;
2. Correctly print the output if one test module test fails.