Enhance dynamic log file naming to be composed of Flow Name and run time timestamp

[fharper]

In user settings you can define a "Logging Directory" and if you do the system will send the Output Log (Results view messages) to a file in that folder.  The name generated is Alteryx_Log_ + an apparent sequential number, example: Alteryx_Log_1519833221_1.

This makes it impossible to identify which flow it is associated with and which instance of execution simply by looking at the name, you have to parse the content to see the flow name and start/end timestamps.  For trouble shooting we want to be able to look at the list of file names and quickly see which file, of possibly hundreds of files, we need to look at to see what went wrong.